My sister bought this game, since she is a HP nut. Here's my review:
Graphics: 9/10
They are pretty much superb - very clear and detailed, although sometimes it gets a bit too bland.
Sound: 8/10
Music ripped straight from John Williams' soundtrack is great, voice acting is pretty good, although you can tell the difference between a Yankee doing an English accent (which is what they did), and it's pretty annoying, especially after hearing so many yanks and their aussie impressions. Ugh. Sound affects are ok.
Gameplay: 5/10
Here's my main gripe with the game.
It's great as an adventure game, since it mimmicks everything from Zelda: Item-button assigning, auto-jump...the whole kit 'n' kaboodle, but all your challenges and dungeons are pretty much void of any point, other than to 'prove' that Harry Potter is the hero and only he can do it. Take this scenario: You go into class to learn a spell. But you don't learn it. The class doesn't learn it. The teacher sends you, Harry Potter, into a death-defying dungeons full of lava-shooting beasts, mace-ridden traps and life-sucking ghosts - to get a spell book. Once you retrieve the spellbook, you learn the spell. Problem I have is that the rest of the class learns it as well, without having to go thru that same challenge.
Here's another example:
Neville Longbottom is stuck behind a 'cursed' wall hanging that won't let him out. Hermione is standing there, waiting for you. You talk to her, and she says 'Harry! Go into the greenhouse and get the spell so that you can free Neville! Only you can do it! Hurry!' How he got in there (other than his own stupidity) is not explained, only that he is there, and that only you, Harry Potter and not the far-more-experienced teachers, can get him out of this 'life-threatening' situatution.
There really is no point to the while game, other than that it leads to the final boss battle with the Basilisk, and you, Harry Potter, realising that it was the diary of Tom Riddle aka Lord Voldemort as a student (ooops, can't say his name! But i DID! OH NO!) that was behind the murders at Hogwarts.
All in all, it was an easy game, with much trial and error style gameplay.
The only saving grace of this game is flying on the Nimbus 2000 and Quidditch. Flying around Hogwarts gets pretty boring after a while, but it is damn fun. Too bad this free-form mode wasn't expanded further than just providing a few rings that give you Jelly Beans - oh wait. They're 'Bertie Botts Every Flavour Beans'. Quidditch is fun, for the four games you play, and learning to play is quite good too.
Too bad Quidditch World Cup is just balls.
Replay Value: 4/10
Once you play it, you won't go back. UNless you are dumb enough to try and collect every wizards and witches card, cause it becomes a game of 'Rememberance', since you have to remmeber who has what card so that you can trade with them later when you have teh card they want. Wind Wakers Nintendo Galley was more fun.
Connectivity: 4/10
As with most GC/GBA link games, the fact that you need all these things to get some secret levels and whatnot is pure frustration. Good thing my cousin has teh GBA CoS game, and a GBA. But this sorta thing isn't really a good even as a gimmick. But it does get the money exchanging hands for die-hard fans.
OVERALL: 6/10