Saw Transformers 2, 'Revenge of the Fallen'. If you haven't seen it yet, stop reading here. Spoilers follow.
I'll start with what I liked about the movie. I trooped to the theater because I wanted to see the Autobots again and I sure wasn't disappointed. There's an early fight scene at Shanghai with Optimus Prime and the rest of the autobots(sans Bumblebee) stalking and bringing down two decepticons with the help of a secret US-lead international taskforce under Major Lennox (Duhamel). Back at the US, Bumblebee had a scene all his own terminating mini-monsters.
Here's the rest of my take on the second Transformers movie.