Awesome eye candy! Fun to watch, lots of humor and a little more "grown-up" than the first movie. Saw it in IMAX - worth the extra $$
It is waaaay too long, but still leaves plot holes. The language is a bit strong considering how much kids love Transformers. The Autobot Twins were unnecessary and annoying.
Overall, you should definitely go experience this in the theatre. The effects (visual and sound) are incredible.