Tank i agree with you completely about the fight scenes, they were ridiculous, and the romance although not being great, could have been alot worse.
But to me, the toilet "humor" and sector 7 bullshit ruined the movie. Atleast the Marines at the start were believable, i thought the movie was pretty good until the scene with the autobots hiding behind the house, and when sector 7 and the main actor came in, it felt like something of a police officer from Home Alone, not a M rated movie. After putting up with 30 minutes of sector 7's leader, and shameless storytelling from sector 7 of the whole fucking movie, i really did feel like leaving, that 30 minutes destroyed the film to a point were i couldn't even enjoy the last bit of the movie, because of the horse shit that preceded it.
So for me, Bay ruined it, it had hope, but it felt rushed, and missing just a special something as a whole, because of the comic relief and childish acting, i would give it a C-.
edit - oh and the scene were the autobots introduced themselves was super gay, it seemed like a scene out of final fantasy it was that lame. The movie was enjoyable about up to the point were the helicopter transformed and attacked.