Re: Optimus Prime's characterization (Spoilers)
I think I covered this on the review thread. Once Optimus had the chance to take the kid gloves off in TFTM, he was once ruthless SOB. Ordering the Dinobots to destroy Devastator, mowing down every Decepticon that got in his way, and confronting Megatron with the intent to kill him. And had he not blown his chance by wasting time mocking a pleading Megatron, he would've done to him what Bay's Optimus did to Megatron and Sentinel. It seems Bay's Optimus just watched TFTM on the break and got a little genre savvy with traitorous scum.
Like the 10th Doctor would put it: "No second chances. I'm that nice of a man."