My view on this series basically boils down to this: many rehashed elements, not much substance. If you want to watch this just for the mecha aspect, it's pretty enjoyable due to the very high production values. If you're looking for a good story and solid characters to go along with that action, well, you might be disappointed. Unicorn builds upon previous Gundam series set in the Universal Century (UC) Timeline, so you shouldn't watch this until you've watched the UC Timeline's core content (0079, Zeta, CCA). And because Unicorn came out after those other Gundam series, I'll use some comparisons to highlight the places I feel Unicorn went wrong. There shouldn't be any spoilers for any series in the main review, just comments on the general direction of things. However, there is a spoiler section at the end that covers some things specific to Unicorn that I felt I needed to address. Despite the issues I have with this series, I would still recommend Gundam fans to watch it, especially since my opinion seems to be of the minority. Anyway, on with the rest of the review...

Story:
The story of Unicorn starts off using a formula that has become very common for Gundam series. Basically, some event kicks off around the MC's home area, causing them to get pulled into a conflict. In 0079, Amuro was caught in a fight or flight situation within his home territory, and the same was true for Kira from Gundam Seed. Zeta Gundam was different in that Kamille put himself and others in harm's way due to his rebellious nature, rather than for some noble reason. I felt this was important to bring up, because it marks the difference in the MCs of the various series. Some start off just trying to survive or do the right thing, while others are displeased with the life they have. In Unicorn, things are a little weird. The main character, Banagher, starts off a bit like Kamille, in that he makes choices that pile up and result in him being pulled into a conflict. Although, unlike Kamille, it's almost as if Banagher's making an instinctual decision to be involved, since most of the time there's no reason for him to even care. It's like he realizes he's the main character of a show and is responsible for moving the plot forward. To make it even worse, he routinely blames other people for his continued involvement, even though he's given several chances to leave. That mentality gets old really fast.

As for the actual story-line, it follows the mystery of Laplace’s Box, which rumors say holds some great power. I really do mean rumors, since each side has almost no idea what the box is or where it's located. Yet, apparently, this rumor is important enough to basically revitalize a war over. Most of the story involves the various factions traveling place to place and fighting as some clue about the box's mystery is revealed. When the mystery behind the box is finally revealed, well, it's pretty underwhelming. It's hard to explain why I felt this way without spoiling anything, but essentially its significance is overplayed. There's some major logical missteps the writers made in trying to make the box seem important (see the spoilers sections if you want to know the specifics of what I mean). In reality, the infrastructure of where the box is located is actually more useful than the box itself. So once the box's secrets are revealed, some pretty important monologuing occurs, but it's not clear whether that amounts to anything. There's basically zero conclusion to the initial premise of the story, which is, "War is bad, so stop killing each other all the time." Instead, the ending is essentially, "Alright, cool, we found it, the end." All in all, the story is a real mess that seems completely lost and ends up amounting to nothing.

Characters:
Overall, there's the same standard affair of characters as nearly every other entry in the UC timeline. I found this boring since the presence of some characters felt forced and only done to appeal to fans. Also, many characters have either no character development or very erratic changes in personality. I've already gone into a bit of detail about the MC and his actions in the beginning, but in terms of the entire series, he has almost no character development. As stated earlier, he likes to blame others for his problems. Kamille from Zeta did this, but it was a bit more reasonable since people were doing some pretty nasty things. Most importantly, Kamille's complaining decreases over time, and he becomes a person of action. Banagher, however, complains all the way from episode 1 to episode 7. In the end, he never seems to reach any real resolution with the actions he made, the actions of others, or why the whole mess started in the first place. Ultimately, he fulfills the strategic role of a Gundam pilot and not much else.

As for side characters, many of them also exhibit no character development. Now, character development is not always needed to make for a good show (see Baccano!), but there's a disturbing amount of still characters in Unicorn. Although, there was one character that seemed like they were trying to make up for this void by flipping personalities every couple of episodes. These changes came across as extreme and unsubstantiated reactions whenever they occurred. It was kind of like, "Oh, I guess that happened." So, again, like the story, the characters are a mess.

Combat:
This might seems like a strange category, but due to the core of the Gundam franchise being about mechas blowing each other up (IMO), I figured it was important to discuss this in detail. While past Gundam series have always had a decent case of what I'll call Dragonball Z Syndrome (i.e. talking in the middle of a fight), Unicorn has a near terminal case. The flow of combat is constantly interrupted by impromptu conversations held between pilots, even when they are enemies with each other. Although I'd make the argument that past series would be better if the flow wasn't interrupted as much as it was, it never got to the point where I was actively groaning that I hope they start fighting again.

In regards to combat strategy, this series basically has none. In past series, whatever factions the MCs belonged to would come up with strategies to win the battle. In other words, there was a good sense that these were somewhat realistic, strategic military battles. Unicorn's battles feel like poorly thought out skirmishes, where each side hopes that their fighters are stronger than the fighters on the other side. This is a little bit understandable since the scale of the conflict in Unicorn is smaller than the earlier series, but still, the faction leaders could at least put a little bit more effort into their combat plans.

In regards to the individual battles throughout the series, very few people are shown using any basic strategies. Mostly they rely on magical shields and flying pod lasers to fight and defend. I think a character used an asteroid as cover once in the entire series. It's really disappointing to see this as Gundam has a history of pilots making the best use of their environment in order to win. Instead the pilots use their mobile suits as nothing more than amplifiers for their pre-existing special abilities. This is a problem I've had with other Gundam series as well, where it feels more like a super-robot show rather than a real-robot show, but Unicorn is one of the worst offenders yet.

Expanding a bit more on the pilots' abilities, people like Amuro and Kamille were decent pilots when they started out, but they weren't great. They basically had to rely on their natural talent, their usually OP mobile suit, and the support of other characters to get them through a battle. As time went on, they became very good pilots, and combined with their other abilities, they became extremely effective in battle. In Unicorn, this isn't what happens. Banagher can immediately pilot his mobile suit extremely well and there's almost no development in his fighting ability. So not only did the writers forget to develop his actual character, but they forgot to develop his physical and mental attributes as well!

Art/Sound:
Generally speaking, it's all very good. The animation looks great, with the mobile suits being particularly well-done. The sound effects and BGM are also great. The art quality is basically the only thing that saved this series for me. So even though I found everything else sub-par, the battles are still fun to watch.

Voice Acting:
I watched the English dubbed version and the voice acting was quite good. Everyone's voices seemed to match up with their intended characters, and the performances themselves always matched up to what was happening on screen. In other words, no complaints here.

Conclusion:
As a whole, Unicorn really disappointed me. The visuals combined with it being set in the UC Timeline made me hope they would be doing something interesting. Instead, it was just a compilation of poorly re-imagined characters, the inclusion of elements that dragged past series down, and generally poor writing all-around.

Spoiler Stuff :
Seriously, don't read any of this unless you've seen the whole series.

(Spoilers)
New-Type Stuff:
This connects to the disruption of combat mentioned above. While many other Gundam series have had the same out of body things occur during fights, none of them seemed to break up the action like Unicorn did for me. Also, very few people express shock when it happens. I know we’ve seen it before in past series, and that the universe is probably used to new-types by now. But, I still think communicating telepathically or spiritually with another person would freak most people out.

Banagher’s First Kill:
Banagher doesn’t know he has killed someone until he is told after the fact. He expresses shock, but then gets over it by the end of the scene. It seems kind of strange that it isn't ever brought up again in any detail given how much he complains about killing in general throughout the rest of the series.

Laplace’s Box:
The location where it is found is actually more useful than the box itself, since the location has infrastructure that allows Mineva to talk to all of humanity at once in an attempt to change their mind on how to govern space people. Yet, there's no indication of whether it worked. There isn't even a single scene of the general public watching her broadcast. The two ship captains are also seen clearly ignoring what she is saying as they discuss getting drinks together. It's strange that the whole series revolves around each faction arguing about what the future should look like, and then no one listens when someone lectures them about it. Also, the extra article in the founding principles only holds importance if people want it to. The current government can just say, "We didn’t sign that into law." Not to mention people have never operated under the belief something like that was ever true, so why should it hold so much weight all of a sudden? If something like that was important enough to the general public, they would have made it a law already. Clearly a large portion of people just flat out disagree that the space-noids should have more self-control, so it's not like some 100 year old slab is going to change their mind. The only truth is the one people choose to accept.