I saw this yesterday and it was an awesome robot-bash-spectacle! It wasn't perfect, and the ending felt a bit rushed (it would've been nice to get somekind of post-action glimpse at how things work out for the main characters). But all in all it was good, or maybe even awesome.
It's a rare thing now a days to see a property-based movie where I actually believe some things can be possible (I was ready to believe that Bumblebee and Optimus Prime could die, and I did not see Sentinel Prime's betrayal before it happened). It might be that I'm the only one who felt this way, but for me that was exciting - it made the movie really tense.