As nice as the trailer looks, I'm not feeling it. I've been burned too many times by Bay and his Transformers movie to put any faith and/or trust into Age of Extinction. Judging from the posters and the trailer, it looks like the humans might be getting more screen time than the actual robots. The designs, despite the new versions of Optimus Prime and Bumblebee, are pretty much the same mess from the first 3 movies. And just because the trailer doesn't show off the bad qualities of the past movies (the unnecessary humor, unlikeable characters, zero character development, the racist stereotypes, etc) doesn't mean it won't be in the movie. Trailers have the tendency of showing us what the studios want you to see rather than any major flaws it might have.
These are just my opinions and the final version of the film might prove me wrong. Until then, I'm not gonna get excited for a trailer that may only be giving us false hopes and empty promises.