1; WTF is the random scene blowing up the weasly house? Doesn't add anything to the story.
2; The bad guys spend all this trouble to get some units into hogwarts, but draco and snape are the only ones really doing anything. They might as well have knocked on dumbledore's door and shot him, no need for all the hassle
3: I know now because my gf told something about the next book, but wtf at snape hushing harry instead of zapping his ass. If it is supposed to be a hint make it a bit more clear.
4: if the horcrux in the cave is fake, why did DD have to drink that magic water? Someone else got the real one out without removing the water? just grab that thing and bail out?
5: the movie is named the halfblood prince but the only thing mentioning is a random book that doesn't really influence the movie and a snap oneliner.

1. Should have been taken out of the movie. Could have used the time for more Snape stuff.
2. Should have been less shots of Malfoy fiddling with the cabinet giving more time for combatty type stuff at the end.
3. Again, more Snape stuff would have helped here.
4. It works that way because that's the way it works. It's a story.
5. Movie needed more Snape.

Cliff notes: Movie needed more Snape.

I am rereading Deathly Hallows and the whole crew are at the Burrow for Bill and Fleurs wedding after escaping Voldemort to get there. How the hell are they going to change all of that for the next movie? Or will the Burrow be back to normal in time for that.