Second of all there's this great timely speech from Optimus Prime, which I will paraphrase thusly
Why should we help the humans? They are a weak and violent race, but they are a young race full of hope, and I see something of ourselves in them. Everybody deserves the abiity to determine their own future and we must insure that they may do so . . .
At this point I'm going "Ooh, shoehorned Iraq War message, deep."
. . . by finding the Cube and preventing Megatron from getting the Allspark.Subtexty.
A proper review and analysis to come, but let me be the (fifty) first to tell you to go to the theater early in the morning and buy one matinee ticket and one evening ticket, because you will want to see it again.