Update: The live play of the game is finished. From what I saw it was a multi-hour play through the entire game as the Autobots. Of note is the game seems to have levels that are just boss fights where you are fighting the enemy (say Devastator, Seekers, Grindor, etc) while fighting weaker minions at the same time and staying alive. Victories were often anti-climatic with a quick cut to the villian's death and then the level achievement screen. Sadly I got distracted and missed what turned out to be near the last level when play as Jetfire and the merge of Jetfire and Optimus against the fallen so no clue how the ending was.
Over at justin.tv someone is live-casting playing Transformers: Revenge of the Fallen The Game for the 360. I don't know how long its been up or how long the video will show the game. Click here to watch. Thanks to Jeff for the heads-up.