Time for counterpoint.
The movie is all about the giant robot action. Anyone expecting Shakespeare or Citizen Kane is being totally unrealistic, but if you think this is all silly and insubstantial, remember the source material. Also consider that much of the movie circles around the Transformer-to-teen relationship for the first half.
I did not like the mechanical designs, and having seen the movie, I'm still not a fan of them. But they do work, and work well. Five seconds into it, it ceased to be an obstacle for my enjoyment of it. While somewhat hard to tell apart given the shooting style (quick cuts spliced together don't work for me), they are convincing on-screen.
As for product placement...talk about fucking ridiculous. Seriously, this is about the most fatuous quibbles I've heard anyone come up with. It has more to do with people's irrational hatred of Michael Bay and the "he sold out!" mentality that's only in vogue if you're a "free thinking" college puss. As if we live in a world that's not overflowing with branding...it makes sense to see Nokias and Mountain Dew machines randomly. But, to close this one off, who can question the sheer awesomeness of Dispensor?
Taking itself too seriously? I wonder if you saw the same first half I did. The Decepticons came across as a real threat, while the Autobots came across as peaceful and having to adjust. The already mentioned quip from Jazz makes sense in the context in which they learned the lingo, so just quoting it and saying, "it's stupid," simply doesn't tell the whole story.
With regards to character development, I agree that they weren't personalized much. But while more personality would have been nice, it's because of the perspective in which it was presented...the human one. Otherwise, the movie appeals only to fanboys and flops hard. This is what the sequel's good for. On the good side, Sam's a good character, whose interactions with Bumblebee, Barricade, and Optimus Prime represent the best non-action aspects of the movie.
When all's said and done, it's not going to be in the top ten of the greatest movies of all time, and not even in the top hundred. It could have been better, but to say it was total shit is merely one person's opinion. In this (very prejudiced against it beforehand) person's opinion, though, it was a whole lot of fun and well worth the ticket price. I'm taking my nephews to see it this weekend, so that's another $20 it'll get from me.