It's not a bad game but it's easily the most overhyped game I've played this year. I'd describe it as a super generic RPG with a Harry Potter skin. The best thing I can say about it is that the game is very pretty. Hogwarts itself is lively and is pretty fun to walk around in. Everything else, though, is just sooooo generic.
Let's start with the magic system itself: In combat it literally boils down to using the right color on the right enemy. If an enemy has a red shield, use fire. If an enemy has a yellow shield, use your yellow ability. Other than that, just spam your magic until they die. You can dodge but enemies are usually pretty simple and telegraph their attacks hard. For a series so known for its magic, most of the magic boils down to "stun enemy" and "deal damage".
Outside of combat, magic is painfully boring. Your main character will also constantly spoil basic puzzles for you. "Hmm, a rock, perhaps I can use MY LEVITATION SPELL". "Oh, cobwebs are blocking the way, perhaps I can use my FIRE SPELL!" Everything boils down to basic interactions like this.
There's little to no roleplaying, your choices don't matter and boil down to being the nicest guy ever or being an arse for no reason. The story is linear. Your house changes your sleeping area and your clothes and some dialogue but that's about it. The story is very uninspired too, you play as a person with amazing ancient magic powers that nobody else has because you're the chosen one and stuff. Your professor is helping you unearth the mystery of why you're so special while stopping the bad guys from doing evil stuff. Nothing exciting imo.
TL;DR: I guess if you really love Harry Potter you'll enjoy the game for the references they make and magical feel to it, but outside of Hogwarts it's really a pretty generic RPG. The combat's repetitive, the open world feels empty and boring, the game overstays its welcome by being so long, etc. Overall I'd only buy it on deep discount, like $10-15 or something.
Edit: Oh, and there's no Quidditch in this game. Instant 0/10!