While it adds some new touches; the next gen Harry Potter series still has a long way to go.
Harry Potter and the Half-Blood Prince (HP:HBP), adds some nice new mini-games, more locations surrounding Hogwarts, and some nice items to fetch and search for but that's about it. You don't play events directly from the movie, which is good and bad at the same time, and the voice acting for some of characters is horrible. Don't get me started on the graphics and the animations either, they're pretty bad...almost early Xbox 360 bad.
The big question though is, is it fun. Yes, it is very fun. Dueling is awesome, potion making is probably the best thing in the game, and even though the Quidditch mini-game is not full Quidditch, it's still nice to have it put in the game. HP fans and fans of the last game should definitely check this game out, it's well worth your time.
One thing I ask all of you is this, why hasn't EA made a HP rpg game? They have Bioware now, who is more than capable of making outstanding rpg games. We have one more book left and that's it. I'm not sure if EA owns the rights to a creative license but here's hoping for a great HP rpg. I could care less about being in HP shoes, as long as it's in the universe. There's so much potential for a game like that, it would make some nice cash for EA. The HP game on the GBC was an rpg and it was great. For now though, check out HP:HBP.