Roger Ebert's review of Transformers: Revenge of the Fallen appears to be considerably more entertaining than the film itself:
Transformers: Revenge of the Fallen is a horrible experience of unbearable length, briefly punctuated by three or four amusing moments. One of these involves a dog-like robot humping the leg of the heroine. Such are the meager joys. If you want to save yourself the ticket price, go into the kitchen, cue up a male choir singing the music of hell, and get a kid to start banging pots and pans together. Then close your eyes and use your imagination.
The plot is incomprehensible. The dialog of the Autobots, Decepticons and Otherbots is meaningless word flap. Their accents are Brooklyese, British and hip-hop, as befits a race from the distant stars. Their appearance looks like junkyard throw-up. They are dumb as a rock. They share the film with human characters who are much more interesting, and that is very faint praise indeed.
Ebert writes more about the movie on his blog:
The day will come when Transformers: Revenge of the Fallen will be studied in film classes and shown at cult film festivals. It will be seen, in retrospect, as marking the end of an era. Of course there will be many more CGI-based action epics, but never again one this bloated, excessive, incomprehensible, long (149 minutes) or expensive (more than $200 million). Like the dinosaurs, the species has grown too big to survive, and will be wiped out in a cataclysmic event, replaced by more compact, durable forms. ...
The action scenes can perhaps best be understood as abstract art. The Autobots and Decepticons, which are assembled out of auto parts, make no functional or aesthetic sense. They have evolved into forms too complex to be comprehended. When two or more of the Bots are in battle, it is nearly impossible to distinguish one from the other. You can't comprehend most of what they're doing, except for an occasional fist flying, a built-in missile firing, or the always dependable belching of flames.
I'm surprised that Ebert thinks the film will make a huge amount of money. My kids saw the first Transformers but have shown absolutely no interest in seeing them again, thus robbing me of several opportunities to see Megan Fox running in slow-motion. Films that feed dad's nostalgia for childhood don't go over well in my house. No amount of pleading on my part could get the family to see Speed Racer.