More of a collection of minigames with a partial story thrown in.
In The Half-Blood Prince, you do 4 things:
Quidditch
Potion Making
Dueling
Advancing the story
Quidditch involves flying through rings until you catch the snitch. That's it. You can't do any special moves and it's boring.
Potion making is pretty fun but is pretty easy. You combine the said ingredients to make a potion. Unless it's part of the story, you can't actually use it.
While dueling, you can get up to seven (I think) attacks to use. It's alright, but you can spam 2 and easily win.
During the actual main story, you just walk to a spot and watch a cutscene. Unless you've read the book or seen the movie, you will not know what is going on.
While you are walking to your destination, you will randomly duel, play quidditch, or have to make a potion.
There is really no thinking involved in this game. There are no puzzles. It is extremely easy.
I wish they would make either action or puzzle based Potter games from now on instead of these crappy minigame ones.