The movie should have followed through on the emphasis of battle that the book had. A little too much (by about a scene or so) teen romance was depicted, and this wasted time. Hermoine seems to be getting worse at acting as she can't keep a straight face in scenes where she is looking off into the distance or being authoritative. Dumbledore wasn't as convincing as he should have been. The acting was a little forced on his part.
Harry, Ron, Snape, Malfoy, and the Potions Master (Slughorn) were great in this movie.