You can see major improvements over previous games in Harry Potter series.
This is the first Harry Potter to step in the Next-Gen world. The graphics is definitely on par with "next-gen". Character models are very similar to their movie actors. But their face can sometimes be very scary and look very weird. The castle has been redone into a full map with every little corner you see in the movies. It is very fun to just walk around and see the castle filled with life, much like a real-life school.
Some frame rate dips are noticible, especially when outside of the castle near the Hut. Other than that the frame rate is pretty smooth all the way.
The story follows the movie very well, adding little bits of quests from Harry's friends. It will be a near 10 hour experience in Harry's world. The unlockable contents are very impressive, with interviews, behind the scene of various actors working on the game. Worth it? If you don't mind running around the beautiful castle, then yes.