Lacks the excitement
The graphics were okay, same with the game play, but it is too short to make it one of your "got to have games". It shows a storyline plot and adds to it, but you feel like when its over, "wow, how dissapointing." It feels like you only played for 3-4 hours to complete the game, which you probably did if you have it. I played to 8 hours total by either just facing the boss over and over or just playing around flying on my broom. Again, too short.
Not only being short, but they just made it too easy for you. When you have to talk to Malfoy as Crab and Goyle, they make it very easy to get to him and away from him. The battles are way too easy, and their is barely anything to get in your way to getting to them besides getting lost. Too easy to keep you interested.
Well with these obvious reasons, it just seems obvious that it lacks much more than it should. When Harry faced the basilisk in this game it had no thought in making it exciting. The tiny dungeons make it feel "come and finish me, the most boring thing ever". Seriously, the only reason why anyone should get this game is to finish the series which is still not that great of an idea. If you have a old computer get the PC game instead.