I don't think the story is too bad. Of course I am still in the middle of it so that may change.
I also think the friendship story lines are pretty good. I like that each one has its own flavor to it, the Slytherin going dark, the Gryffindor after justice chasing a criminal, the Hufflepuff saving creatures and fighting poachers. Pretty well done I thought.
I guess there isn't much of one for a Ravenclaw, except maybe astronomy guy.
The environments are great, the sound and music is good. The combat is engaging and feels great, although the plant weapons seem underwhelming and I never remember to take potions. I'm playing normal difficulty so maybe you need them more on hard.
Sneaking up to enemies and backstab killing them is satisfying, I just wish there was more of an element of sneaking around Hogwarts and avoiding teachers or prefects. But I guess detention is kind of silly when I'm all over the countryside on a murder spree.
The room of requirement and all the collectables are pretty good. The Merlin trials have some variety, they might get old once I really focus on finishing them all. I haven't bothered much with the broom racing, I have 1 broom upgrade done.
The only real disappointment is the lack of a morality system, which I know is very hard to implement. If going dark caused dramatically different main quest branches it would be cool.
I'm around 35 hours in, I'm in Winter and waiting to start the fourth trial. Working on finding the phoenix at the moment. I think my collections percentage is around 50, and I'm still really digging the game.