A quick review of the first movie:
"Transformers" from two years ago was less than I would have liked. This was partly due to Michael Bay's trademark "shakeycam" and quick-cut style, that makes it hard to tell exactly what's going on and leaves the viewer slightly nauseated.
More of the dissatisfaction was due to the decision by the production staff that the general public needed the first movie to introduce the general idea of the Transformers, living alien robots who have normal thoughts, hopes, dreams, and even emotions much like humans. As such, much of the movie was focused on humans, not robots.
A degree of dissatisfaction was in the juvenile sexual and biological humor.
In comparison, the sequel, "Transformers: Revenge of the Fallen", had even more juvenile humor than the first, however, the Transformers themselves were not as actively involved in this humor as in the first movie. (Caution: much more crude language than the first movie. Not for young kids.)
Again, much of the movie content was focused on the humans, primarily on Sam and Mikaela's relationship and Sam's parents' relationship with him. However, despite the parents being involved through much of the movie (letting us learn much more of their personalities and of the family relationships), these interactions did not pull from the Transformers for whole scenes at a time like before.
The big improvement in "Revenge of the Fallen" is that the focus throughout is primarily on the Transformers. They are primarily "in character"; while some characters are more slapstick in personality than others, characters are consistent. And much more character is developed, particularly among the Decepticons, which was a real lack in the first movie. Most of the banter is in English, as is appropriate since they have now been here for two years. And there is good banter between them.
Action does come far more often and more strongly than in the first. In the first, there was little injury. Jazz was significantly damaged (referred to as dead) and one human was skewered by Skorponok, but that was about it. In this one, we see humans getting blown up (though not bloodily - we see firey explosions) and stepped on (again, with blunt trauma, not bloody), and we see lots of Transformers getting slagged. We see them with holes melted through themselves and fighting on. We see then repairing themselves with internal self-repair mechanisms, reattaching limbs, using parts from others for repair, and returning to battle. In fact, it seems (which answers a host of questions) that they can be repaired from most injuries unless the head itself is destroyed. Which indicates that perhaps Jazz can be repaired, provided proper resources. (Side note: As many already knew, Jazz is not in this movie. He will not likely return in his old form, as the GM Pontiac line is being shut down and Jazz's Solstice mode will no longer be promotion for GM as it was before.) This movie is far more violent than the first.
We see large numbers of Transformers on both sides, many getting slagged without so much as an introduction by name. We meet others who were surprises, and some who have aspects of their original animated series story involved (not giving any spoilers here). We see Cybertron, though many fans might not like how it looks - remember, the planet's dying with the absence of the AllSpark.
As far as the Fallen himself, let's just say this. It's not an analogy or figure of speech, not just a title on the movie, and NOT Megatron. His backstory is not the same as in the original storyline, but it's a lot closer than many had hoped.
For the production itself, yes, Michael Bay still had a lot of "shakeycam", but it's a LOT better than before. There were battle scenes where the camera was far enough back that we could see several fights going on at once. And yes, we could see several entire transformations. For those who might complain that the transformations weren't always executed the same way, they need to just remember that these are very complicated transformations that can be done a number of different ways for the same final modes; many of the toys can even be transformed different ways, say arms before or after the torso. But overall, it's easier to see what's going on. Not perfect, or even close to perfect, but better.
And there's plenty of room for a sequel. Or several.