Overall Feeling:
Harry Potter and The Half Blood Prince is a terrific game that truly captures the essence of the book/film. This isn't merely another cut and paste movie game as there are several segments where the game truly shines due to the originality of developer EA Bright Light. If you're a Harry Potter fan then the game is a must play as it is the quuintessential Harry Potter experience.
The Pros:
The visuals really capture the feel of the movie not only due to the character models but the design of Hogwarts itself. Participating in wizard duels is fun and it captures that intense feel from the movie. Potion making is fun and provides a nice challenge. The game has several unique sections and level scenarios that really help it shine from other movie games.
The Cons:
There could've been a bit more content to the game as it's a bit short. A few sections can be a bit buggy or unpolished as one scene had a mouth of a character not move despite speaking.
Movie games are probably the most schizophrenic genre in the game industry.