I've liked most of Bay's movies in recent years with the exception of Con Air mainly..
Personally, I felt this was one of his worst. The first 1/3 of the movie flowed well, but towards the beginning of the second act, after the rest of the autobots came to earth, the film just seemed to fall apart in terms of character development, scene development, plot holes, and transitions from one scene to the next..
Here's an example..
The transition from Hoover damn to L.A.. Bumblebee is being escorted via convoy. Prime and the rest of the autobots intercept the convoy, turn and follow in close proximity.. Bay then cuts to wide shots showcasing GM products ..
Enter the final act.. All the transformers should be in the same location. Bay had been building up the importance of protecting the all spark and Prime is nowhere in sight.. Barricade attacks, starscream attacks. Prime, the autobot leader, is nowhere to be found. 10 minutes later they cut to the shot of Prime rolling in.. Where did he go? Off to the local car wash for a rinse and wax?
Another observation which has been voiced already was about Jazz. He was in the film all of 5 minutes, he could have been cut and nobody would have noticed.
One laughable moment towards the end of the film, Starcream makes a bombing run firing on Bumblebee/Ironhide, both are displaced. The camera focuses on Bumblebee, then pans to sam.. You see Jazz directly in the background in car form doing nothing; parked inbetween two craters. Someone wasn't paying attention or they ran low on the special effects budget..