Good for what it is, a typical shounen battle manga. It's well comparable to the likes of Bleach, Naruto and Yu Yu Hakusho, but so far it's been more consistently good than any of them. In fact, so far it's only been getting better as it advances.
The main character is a pretty typical shounen lead in the sense that he's earnest, hard worker, an unwittingly charismatic idealist, and there's a typical from weak to strong advancement trajectory. The primary difference to most shounen battle manga leads is that he's actually pretty smart. Though he has willpower in spades, and occasionally he's just forced to push through with sheer willpower, sacrificing a limb or two (as in, breaking them, not losing them permanently), but he can formulate a strategy and make use of his friends' unique abilities. That brings me to the second major difference he has to many shounen leads: while his goal is to become the beacon of hope his idol and teacher was before passing on his power to the MC, he realises his limitations and if he has a choice, he never fights alone. He's not fighting to protect his friends, he's fighting with his friends to protect everyone else. That's a refreshing difference from the likes of Negi from Negima, who is also very smart and one of my favourite shounen leads, but has the tendency to try and shoulder everything himself.
The other characters are steadily gaining depth as the story progresses. The cast is huge and still expanding, so understandably most of them get limited screen time, but overall I feel that the author is still "in control" of the situation and managing his cast smartly: allocating the central characters plenty of time, giving the secondary characters enough to slowly develop them, and making the tertiary characters mainly just physically distinctive. From the start, there has been one character who stands a head and shoulders above everyone else in the story, including the MC: his childhood "friend" and rival with anger management issues. Bakugou is such a well written, multi-dimensional character, I've rarely seen such in a shounen battle manga. Female characters are typically a weak point in this genre, but IMO, Hero Academia is doing a far better job developing them and making them feminine (without taking away from their strength) than most other shounen battle manga. That said, I still think that they generally fall short of the male characters of comparable importance. The female lead is pretty cute, and has been receiving some steady character development, but I'm still hoping for an arc focusing on her and bringing her character to a new level of interesting.
Battles have so far been pretty good... I'd say that at its best, Naruto still has better battles, but the author of Hero Academia is certainly putting enough thought into his battles to pass with flying colours in a shounen battle manga. After reading this far, I'm no longer surprised that this manga is now the second most popular in Shounen Jump, after One Piece, the only one remaining of what we once knew as the "big three". The abilities of the characters, their "quirks", are varied and nicely developing, offering new things to see with each new battle. Some battles are quite exciting and dramatic, and there usually isn't too much blathering between moves. The battles aren't too drawn out, but not too brief either. In terms of smartness and intricacy, they still fall behind the best of Naruto and, say, World Trigger, but they're alright.
I hesitate to say this, as it's still nothing amazing, but I think the plot is a tad more intricate than what is typical for this genre. I like how the public opinion of the heroes is actually plot-relevant and a significant focus in the bad guys' plans. Most of the villains are still unfortunately one-dimensional, but I like how the "previous generation last boss" is making a similar attempt to cultivate his successor as the MC's teacher is doing with the MC. You don't often see the future "last boss" developing in parallel with the MC, though in his case, the focus of development seems to be mental, as opposed to the largely physical training that the MC is doing. One thing I consider important is how this author seems to have a clear plan with a defined end point in mind: this will no doubt be a very long manga, I'd say at least 600 chapters, if it's allowed to run its course, but I think, and hope, that the author won't be dragging the story out beyond its natural life span.
The art is mostly pretty great. There has been no noticeable drop in quality so far, the backgrounds are as detailed as ever and the character and action art are actually getting better. I have no idea how the author is keeping this up, considering how brutal the deadlines are. I don't like some of the character and especially costume designs, they can get pretty ridiculous, but it's still nothing compared to the utter jokes that some One Piece character designs are. There's nice variety on the designs, every character has their individual look, and I suppose that's ultimately more important in a story with such a huge cast, than making them cool-looking. The female character designs are hardly the sexiest out there, but for the standards of this genre, they're pretty cute. It's not like eye candy is a selling point anyway, although there are occasional attempts at moderate fanservice.
All in all, it was a very enjoyable read that effectively hooked me until I reached near the end of the translated chapters (131/137) - I stopped reading with a few chapters left, in order to not risk a cliffhanger. At this time, I'll rate it 8/10. If there won't be a drop in the quality, as is always a risk in long manga stories, I'll be happy to keep reading this.