Hm. Just finished the whole thing. Mixed feelings.
I was very invested in the main character, but, unfortunately, I find it really hard to enjoy stories where all the other characters misunderstand the main character and act willfully and hurtfully, even though it's supposed to be humourous. I've always found that kind of humour very difficult to enjoy because I feel to frustrated and sympathetic for the MC. And, if I don't find a lot of it humourous, the actions of most of the characters towards the MC suddenly seem incredibly, horribly cruel - the actions of almost every single character, and especially the teachers. I kept reading because I kept thinking there'd be some significant developments soon, but the developments that occurred ended up being much smaller, much later, and much less satisfying thanI liked, because the MC deserved so much more than that after everything he went through.
This is certainly a very easy-to-read story. I appreciated that it stayed much truer to its premise of the MC having a scary appearance than many similar stories (where the MC usually starts to be drawn much more appealingly after a few chapters because someone has discovered his nice side). It gradually built a lively cast of characters, even though it tended to repeat the same scenario with every new character introduced, and I honestly got tired of the endless stupidity or mindless prejudice many of the characters showed.
I can see why other people enjoyed it. I'm just not someone who is able to enjoy stories where characters are constantly misunderstanding or willfully disregarding the MC's real thoughts and feelings, even when the story is otherwise engagingly written. There were enough genuinely nice or funny bits sprinkled across the story to keep me hoping the MC's situation would improve soon and kept me wanting to read on and on until it did - after all, I became extremely fond of the MC. In the end, though, it stuck to its premise and left me with a "things will be a bit better now," ending rather than the larger payoff I was holding out for.
I think that if you're considering reading this and you're not the kind of person who gets too bothered stories that put the MC in this kind of position, there's a lot for you to enjoy. If you do tend to feel sad and frustrated for the MC, or are just really tired of belligerent characters who always try to get revenge for the perceived dent to their pride with more violence, then be aware that the tone the manga sets in its first few small arcs is reasonably faithfully continued throughout the story; that people whose attitude changes are few and far between, especially for the first third/half of the story.
This is just my personal review, and not at all intended to invalidate the opinions of others who enjoyed it more or less than I did.
(I'd give this 7/10.)