Please note that this is my first review of an anime and also written past midnight at 12:18 AM, so I apologize if this review is slightly scuffed.

The Angel Next Door Spoils Me Rotten comes from a relatively popular light novel written by Saeki-san that achieved a relatively high popularity, causing it to be adapted into a manga, and later an anime. However, because of this order of adaptation and the anime being slightly rushed in production (speculation, not entirely sure), this caused a severe lack in quality in the anime. Herein lies the issue:

Animation

I'll start with reviewing the animation (I'll leave out art for now since it isn't worth mentioning, but if you want to know the art was eh). I've watched a fair amount of shows with mediocre production values, but I don't think I've ever watched a show with this amount of poor quality. Each episode (yes, I have watched all 12 episodes) lacked in movement, in-between frames, and seemed to have such a low budget that it put Lucifer and the Biscuit Hammer to shame. Okay, it wasn't that bad, but it was a huge disappointment considering the trailer showed at least above-average quality in production. As someone coming from the light novel, I'll admit that animation was something I was relatively concerned with. Light novels that become anime generally don't have that great of animation due to the studio not having much to work with. When there is a manga adaptation, the studio is able to fill-in the frames between each panel. However, that is not the case with light novels. This becomes even more of an issue with The Angel Next Door since it's a slice of life, not an action-themed media. Because of this, it seems that the studio decided to drop the ball on this anime and put in little-to-know budget in terms of production. Honestly a huge disappointment, because if they gave the animation their all like Hyouka (a slice of life that put a little too much effort into their animation, but that's a side tangent), this would've easily been a great show.
Score: 3/10

Story/Character Progression

The story here is pretty controversial. A lot of people say that it was awful and very mediocre (which I can see), and others say that it is the best thing they've seen since the beginning of time (which I also can see). I exaggerated that quite a bit, but in my eyes this was a little bit of both. I'm a sucker for the romance/slice of life genre, so when I picked up the light novel I was immediately hooked. Boring/generic shows don't actually bore me, so getting through the first four volumes was nothing. To be honest, I think the way Saeki-san portrayed the characters was much better than the way the anime portrayed them. I'm not saying this as a biased source material viewer, but it's just factual in my opinion. The anime covered so much content (about 3-4 volumes if I'm not mistaken) that the character progression was extremely rushed and oversimplified. The story was pretty much non-existent and the moments of fluff was barely noticeable. If you don't know what I'm talking about, take the apartment scene (no spoilers here). In the anime, this was covered from 4:10 in episode 1 to 10:31. In the novel, this took place a little after chapter two (page 23ish) to chapter three (page 37ish). I'm no professional in this area, so take those stats as you will. To me, it just seems like 12 episodes isn't quite enough to cover such a complex story. The romance to me does seem relatively bland in the anime, but compared to the light novel it's very different. I've had people tell me that the novel is just your average romance slice of life, but I think that you have to really read it carefully to fully grasp what it's about. Amane and Mahiru's character progression is much better understood in the text rather than as anime characters since much of the novel is spent in the thoughts of Amane. He's an introverted character, meaning he doesn't express himself very well. The anime had a hard time portraying that, which is why I think he's better understood in the novel rather than the show. Anyways, with the negatives out of the way, I think the show still did it's best in describing the storyline and character progression. It isn't as bad as it could be, and some parts like Mahiru's interaction with both her mother and Amane's mother were written decently well. If you're here for just the story, this isn't the best anime you could watch but it also isn't the worst anime you could watch.
Score: 6.7/10

Soundtrack and Audio

My brother is a composer and I play a few instruments, but by no means am I a musical connoisseur. However, I will admit that I like the ED. I'm starting with that first because I actually enjoyed the vibe it gave. The animation there was actually sub-par and the music complimented it nicely. It was very fluffy and felt like it had a nice progression from the soft beginning, to the louder climax, and finally petering down to close off the episode. The ED was centered around Mahiru and I think the lyrics and instrument choice showed both her and the show's characteristics nicely. It's a bit hard to understand what the ED is about without prior context (the light novel for example), but it isn't impossible to enjoy it even without reading the source material. Yet another ED to add to my playlist! Now, onto the OP. I have quite a few complaints such as why the heck is the OP for a slice of life show so upbeat?? Yes, you also have Golden Time and Kaguya-sama's OP's, but those have the Comedy genre attached to it. This show, The Angel Next Door Spoils Me Rotten, is NOT a Comedy show. I don't understand why the OP basically has a rapper (ok not literally, but still) in it. The OP is fast-paced, confusing, and while it has appropriate lyrics, is so out-of-place that it's distracting. I had the OP on my playlist for a bit to get a gauge of what the show was trying to achieve, but before I knew it I had removed it from Spotify and never tried listening to it again. Anyways, enough of my rant. The audio effects weren't very noticeable, but they definitely weren't distracting. Pretty standard stuff with rain, footsteps, etc.
Score: 7.2/10

In conclusion, the Angel Next Door Spoils Me Rotten is a big disappointment from such a hyped-up novel. I am very sad to see such a successful light novel not get the anime it deserves, but it's definitely not as bad as it could've been. I would recommend reading the novel over the anime any day. The manga isn't quite up-to-date, but it also isn't terrible. Thanks for reading my review!