I like cosplaying (as in, looking at cosplayers online), so when I saw an entire anime based on it, I was sort of skeptical, nevertheless, it's actually quite fun.

For the animation: +.

Cloverworks have implemented CGI in some of the scenes, and they are all good.
same goes to 2D aspect as well, i think everything animated in this show just looks cool, and awesome at the same time.
What really surprised me though is how the cosplay costumes looked, they are flashy, vibrant, and beautiful to look at on screen.
The photography moments are the parts this show SHINES in, every picture taken just looked stunning.

the characters for me felt pretty decent for the most part:

everything about Wakana and Marin are all very simplistic, and doesn't really "expand" much, they at least have decent chemistry with each other, I was entertained when the main 2 are around with each other.

For Marin in particular, I could say that she is quite relatable, likeable, and just overall, a very fun, silly character, every time she gets into cosplaying, it's always a funny, and comedic interaction, that actually helps with Wakana's character.

Speaking of Wakana, he gets to develop from each interaction with not just his dad, but Marin too. It's all pretty seamless but there's nothing to really expand, because he can't really make cosplays for its own without fulfilling somebody else, since he doesn't have an interest in making cosplays HIMSELF.

Shinju and Sajuna: they compliment Marin and especially Wakana, and definitely for the better, Sajuna in particular shines in that front, having a nice and comedic introduction.

Every single character's personalities, old or young, do feel very distinct from one another, demonstrated by both the voice actors and the writing.

For the story?

it has a very simple plot and premise, and doesn't go TOO far past that simplicity, just like with the characters
The message its trying to convey is about internet culture and it's relatable for the most part, It's at least competent.
It's a slice-of-life after all, there's no like crazy overarching story, and it's for the benefit of this show, as it MOSTLY focuses on the comedy.

After the first cosplay, it gets kind of repetitive at times, because when the cosplays are done, they ARE done, and they are almost never mentioned even for a SINGLE time.

The fanservice in this show didn't really annoyed me THAT much, it isn't too jarring, and it's not an "always" scenario, they don't detract from the experience too much.

Overall, it's a decently-crafted anime, showing other people your interests CAN be very embarrassing sometimes, and this is a decent example of conveying that message.