Transformers 2 was absolutely horrible. If you plan to see it, have low expectations.
It's practically plotless with so many filler scenes to drive you mad. The comedy is ridiculously not funny, and way too much of it. The characters are so flat and shallow to really move anything forward. Sam and Mikaela jump one scene to the next, with awful dialogue and acting. They don't seem to know much about what's happening then you do.
Visually spectacular and totally meaningless mayhem driven shootout/fight scenes which go through the whole movie non-stop. You simply grow tiresome and bored of it. It also clearly uses what Bay shot in Pearl Harbor and Armageddon several times. Even clips from the predecessor are shown quite frequently, not to mention using a plain bland environment for even Bay cannot figure out whats going on in the fights between transformers.
Though, there are a lot of really great money-shots along the way.