Ultimately, Revenge of the Fallen is the most highly budgeted bad movie of all time. Think of all the cliche things that are involved in Michael Bay movies, multiply that by 10, put in some giant robots and you have Transformers 2.
Sadly enough, a fair number of high budget movies are unoriginal in plot and story development, but in one way or another a good portion of them redeem themselves with some level of entertainment. Revenge of the Fallen fails to deliver the entertainment because the plot is uncohesive and haphazard. The only redeeming quality might be the amazing special effects but they are overshadowed by the worst flowing story of all time.
Michael Bay manages to take the concept of movie making, rapes it, and gets away with it by using millions of dollars and the sad fact that the average movie goer is not terribly demanding and is relatively easy to please.
The guys at www.wednesdayisforcomics.com
do a good job of breaking this down on their latest podcast regarding bad movies.
Why is the storyline so haphazard you ask? It comes down to the way the movie was filmed. A large number of scenes were filmed with no idea on how they would fit inside the script. Screenwriters were hired after the fact to fit in the gaps and try and blend these scenes into the movie. Needless to say this style of filmmaking makes for a distorted storyline and a flow that is forced.