I would just like to say that I grew up with Transformers and so I would buy this anyway regardless of the actual quality of the film.
I really liked the first film although there was the odd stupid comedy moment (which not even the cartoons had), but this 2nd film takes that to an all new level. What were they thinking with the script? Is there any group of people that appreciate the stupid characters and the meaningless dialogue that makes the film feel so pointless?
The 2nd film in any series is known for having the visuals ramped up and this one is the same although they seem to have gone completely crazy with it. I wonder if they bought so much resource in to the special effects that they felt they had to use it! It's too much.
I also think that the people that have the final word over which characters to use and the story aren't true Transformers fans. Some of the characters are too far away from the originals and some seem to have been changed just to satisfy the sponsors through some of the heaviest product placement I have ever seen. Again, it's way over done.
All in all, if you're a fan then watch it at least once, if not then I wouldn't go out of my way to pick this up.
For anyone with kids reading this, pick up the 1980s film version which is the cartoon. The DVD should be a good price and will entertain far more than this.