Of the five films under Bay's tenure, the first one is the one that most consider to be the most decent or most competently made. But when one takes a good hard look at it, it becomes clear that it really feels like at least two separate films mashed together.
On the one hand, you've got a military intrigue film about the U.S. Army facing an unknown enemy threat that has the Pentagon stumped enough to call in outside help from young analysts and hackers, while a small band of soldiers are on the run for their lives.
And on the other hand, you've got a whimsical coming-of-age film about a boy getting his first car in hopes of impressing the girl he has a crush on, and his car turns out to actually be an extraordinary being from outer space, who helps the boy get the girl and takes them both on a life-changing, whirlwind adventure.
...And somewhere in there, you've got a Transformers film with Autobots and Decepticons coming to Earth from Planet Cybertron and fighting each other over the AllSpark. This was used as the glue that helped tie those other two films together, but still really feels like Bay wanted to make the military intrigue film while Spielberg wanted him to make the coming-of-age film instead. Thus, the end result feels like a mashed-together compromise.