Saw this yesterday. It is a very nice movie.
Sure, at times the acting is shabby (Megan Fox is particularly guilty of this). Sure, there are too many subplots, all just to lead, somewhat haphazardly, to the epic showdown between the Autobots and the Decepticons. And sure, the ending is pretty obvious right from the beginning.
But this is not why we went to watch it. That's like complaining that Scary Movie 3 did not have a plot. We went to see special effects, and that is where the movie delivers. Robots fighting each other would have been epic enough, top that off with US army technology in action (one particular scene of a dogfight involving an F-22 Raptor and other aircraft was downright orgasmic) and you have got a recipe for insta-win.
The movie also put to skilful use several popular internet memes, including 'what would Jesus do' and an implied 'get to the choppa' among others. Likewise, there is humor interspersed throughout the movie, often involving the Autobots, to add icing on top of an already delicious cake.
To put it succintly, if you are looking for a movie that will explore emotions, and take human-cyborg interaction to a whole new level, you have come to the wrong place. But for an evening of fun and nostalgia with friends, Transformers is one heckuva movie.