Finally got around to seeing this after being swamped for the holidays... I had high expectations based on word-of-mouth but found it decidedly meh. Felt very much like "what if the first movie was made by a normal person instead of insane Michael Bay?" Didn't fall to the same lows, but didn't reach the same highs either.
I think part of me might just be burnt out on the 'Transformers as the scary other' tack the movies have taken, where it's always from the human point of view, and the Transformers are mostly giant monsters fighting and Optimus (and maybe Megatron) are the only ones who really get any dialogue. Growing up on the cartoons and comics where the Transformers were the main characters with their own personalities, where the humans are the side characters and framing... that's always what I liked, and I know that may not work for more general audience movies, but I think it's a large part of why they leave me a little empty. I see the bits we get with Shatter and Dropkick and want a lot more of that.
Still, pleasantly happy that the movie was successful and interested to see what direction they might go in.