Xbox 360, PlayStation 2 & 3, PlayStation Portable, Wii, DS
The Transformers movie focuses on a guy named Sam and his classic Camaro, which turns into this big robot thing with eyes and kills evil car-robots that also have eyes.
Transformers: The Game follows this cinematic thread, and the plot is threadbare. You try not to drive your Camaro over people. You push a button to transform into a machine-guy that apparently is more than meets the eye.
As a robot, you shoot missiles and stuff, and you punch and kick rivals. Quite a few reviewers have creamed the game for not looking great and for feeling repetitive. I would add that the driving physics suck.
On the other hand, the fighting mechanics of robot-vs.-robot are pretty cool. And on my Xbox 360, the visuals are just fine.
You can play as the good guys (Autobots) or the villains (Decepticons), and you get a fairly different experience with either choice. The down side is that it's not terribly exciting to punch and kick Transformers over and over.