It's all underrated!
The gameplay is quite fun: duels, potion-making, walking around the castle BUT it might get boring near the end of the game. The game is also not too long (honestly it took me a few hours to finish it) so it will not make you bored for a long time. When you're lost you can call sir Nicholaus (a ghost) and he will help you get to the place you have to go to. There are also clubs: potion making club, dueling club. You can go there and just do something. It's really fun. In the dueling clubs you've got to learn about five or six spells. These clubs are really fun. You can also cast spells around the castle: there are three or four I think. You can get extra shields (You have to get 250 to collect all) by casting spells at other stuff. Making potions: There are picture instructions on the screen and you've got to follow them. It's on time so you have to be quick. You click on the thing you want to grab and pour it in by pressing the arrow key. Sometimes you have to throw things into the potion you're making (I mean you do the potion in a caulddron). You attend lessons and stuff..... Generally for the whole game you follow the story mode. OH! And quiditch! you just fly through stars that appear on the screen (It's not so good in the game).
Overall: QUITE a good game.