The movies are loud and overblown. The battle sequences are SO LONG. And they are so heavily military. Having said that, my biggest issue with the movies is true of almost any manifestation of these robots, too many humans. Except for Beast Wars there are always meddling people getting in the way. The 3rd MB atrocity was the one most focused on the relationships between the Cybertronians. It also borrowed from G1 story lines. Mostly "Ultimate Doom" which was about using the space bridge to bring Cyberton into Earth orbit. But any true fan would have giggled at Megatron booting Lincoln from his seat like in he did the episode "Atlantis Arise." I digress.
More than anything else is Michael Bay's insistence on appealing to immature male humor. It is insulting and irksome. The 2nd movie is a travesty regarding this. It's only redeeming value was Optimus Prime in IMAX during the forest battle. I nearly cried.
Despite all these flaws there is one thing the movies do. The keep the franchise alive. I got to ride the 3D experience at Paramount because of it. There is a steady supply of creative and unique t-shirts available all the time. Comic books, art, even G1 replica toys. It's heaven for a fan like myself. So NO I don't like the movies but YES I am glad they exist. I own them all and I will be going to the 4th one. Hopefully they have learned their lessons, but I doubt it. Doesn't matter either way because I get to keep feeding my obsession due to their existance..