How do you describe Assassination Classroom? It's a story that's simple, but also unique. It's goofy but also serious. I suppose the best word to describe it would be is enjoyable.
Right off the bat, the reader is sent a handful of mixed signals. The moon was destroyed... by a cartoonish octopus character that can move at Mach 20? And it has to be killed by a classroom of middle schoolers?
If I'm being honest, the first volume is the weakest, the characters are fairly bland, you aren't given any investment into the world, it's alright at best.
But as the series progresses, it's hard not to get immersed into the world and characters of the Assassination Classroom.

In terms of the Story, it's fairly simple but also unique. Which is fine, that's all you need for a manga like this, there's a clear deadline for when the manga is going to end (one full school year), there's practically no filler and the manga progresses in an extremely fluid and constant rate which is friendly to those who marathon.

I love the Art in Assassination Classroom. Sure it's quite simple most of the time, but where I feel the artwork shines best is in facial expressions and atmosphere. The manga is FANTASTIC at making most of the people in the school outside of Class E look absolutely hideous, they have the ugliest expressions and it helps you sympathize with Class E's situation, it's perfect. There's a lot of nature imagery in this manga, animals like snakes and scorpions are used constantly throughout that really adds to the visualization of what's happening, often times this is used to symbolize how the children are moving in their attempts to kill Koro Sensei, but it's used to represent the characteristics of people quite effectively as well. Action scenes are beautifully drawn as well, there were times that I just lingered on a page because of how good it was. These pages are few and far between which makes you savor the ones that you get.

I think the characters are the weakest part of Assassination Classroom. It's not that their bad per say, but it's hard to grow attached to every character (especially when some only have a couple of lines in the entire series). The main cast is quite well done, you're given a good amount of their specific thought processes throughout the manga and there's a good amount of development that occurs across the span of the manga. Some characters just exist for the sake of existing though, especially near the end. While one of the main points of Class E is that each student has his or her specialties, it's a bit hard to keep track of who's good at what or who's doing what, but that might just be me.

In terms of overall enjoyment, I don't think that there was a simple chapter that I didn't enjoy. Even when the students have to take tests it's made exciting and tense. In a bit of a contrast to what I said earlier, I do think that Class E is filled with really enjoyable characters. There's witty dialogue constantly, which is paired with atmospheric art which gives the reader a good time. Despite the warning at the beginning that the world will end if they don't kill this unkillable teacher, the mood is extremely light-hearted. Every chapter, no matter what the class is doing, was highly enjoyable to read through and I think this is the shining factor for the manga. It's just a class coming together, having a good time, improving their academic abilities while trying to also kill their teacher. The action sequences are tense and cleaver, the classroom parts are silly and cartoonish, and I think that the manga finds a strong balance between serious and the "everyday stuff" that works phenomenally.

Scores:
Story: 8/10, simple, but unique, flows well throughout the manga, there's a set deadline and it doesn't overstay it's welcome.

Art: 9.5/10 Very good atmospheric and expressive artwork, action pages are very nice to look at, everyday art is a little average and plain (nothing bad about it but nothing particularly great)

Character: 8/10: most of Class E has good chemistry but some individuals can be forgotten, some characters nearing the end seem to exist for the sake of existing

Enjoyment: 10/10 There wasn't a simple chapter I didn't find myself not enjoying to some degree, there's plenty of serious and comical moments, finds a good balance between these two and I loved every second of it.

Overall: 9/10
The premise is unique, the story flows at a consistent pace throughout it's run. The main cast of characters are very fun and you're given a good view of their specific thought processes. The art is enjoyable, especially on character expressions and atmosphere. Aside from a couple of moments around the end, I don't have any problems with this manga. I highly recommend it if you're looking for a fun, surprisingly emotional story to read. Once you get past the first volume it picks up fast.