I can't believe I'm saying this about a Michael Bay movie, but it could have done with less of the talky bits. There were some sub-plots and minor characters that only made the movie drag. If you're watching the Transformers, you're watching it for one thing and one thing only: to see giant robots fight. Have however much plot you need for giant robots to be fighting, but leave it at that.
What I also loved was that this movie was essentially a three-hour commercial for Hasbro, General Motors, and the U.S. Military. Of course, the military thing is no accident: the Pentagon's standard policy is that in movies that portray the U.S. military well, they supply the studio with military equipment, personnel, footage, etc. This was definitely one of those movies. (After all, one of the ways that the movie showed that the Decepticons are truly evil--aside from their murdering civilians, glowering expressions, glowing red eyes, and sinister voices--was that they desecrated the American flag.)
God bless Michael Bay, and God bless Optimus Prime.