Likes
The Action:- Everything that TF2 improved on in terms of the first (i.e. fight choreography), TF3 improves even further. Glorious, crystal clear slo-mo abounds, though in my case it was helped by IMAX.
The 3D:- felt right. Not a shit add-on at all.
Optimus the Badass:- Holy fuck does he do some awesome shit in this film. And his weapons kick ass - even his energon axe from G1 makes an appearance.
The Comedy:- is not nearly as goofy as the second film. Ken Jeong hams it up a bit, but its quick and doesn't overstay its welcome.
The Kills:- from Bumblebee blowing Soundwave's head off (via an upwards shot through his torso), to Optimus punching right through Shockwave, and more, the robot-on-robot violence is glorious.
Leonard Nimoy is Galvatron as Sentinel Prime:- he was great, and all the nerd shoutouts were well done - the Wrath of Khan quote:- "the needs of the many outweigh the needs of the few" was especially amusing

No Twins:- need I say more?
More bots get things to do:- unlike TF1 and TF2, its not just Optimus and Bumblebee you get to see in action, though they still do the lion's share of the cool shit.
Soundwave:- as a Mercedes SLS he works really well. His execution of Q was just .. shockingly evil. Poor guy.
Shockwave:- Looked awesome.
Humans don't own the Decepticons single-handedly:- the Decepticons have clear superiority in Chicago, smashing human attempts to brute foce them with their ships. The humans instead fight in more clever ways (sniper rifles vs the eyes, for example), and their mild vulnerability to grenades is elaborated upon.
Of course, some cruise missiles come in at the end, but its hardly decisive.
Optimus subverts good guy cliches and kills Sentinel Prime whilst he's down:- with Megatron's shotgun-like cannon. Good, I hate it when the bad guy is left alive only to get up and try and kill the good guy at the last moment.
Dislikes
Optimus subverts good guy cliches way too fucking much and kills Megatron like a cold-blooded sneaky sadist:- Much was made in the last film of Optimus' merciless way of killing - and it never bothered me. Until the very end of this movie.
Basically, after a long, awesome fight between Sentinel and Optimus, Sentinel gains the upper hand and cuts off one of Optimus arms, then pins his other one with his blades. Carly rouses Megatron to fight Sentinel, appealing to his baser instincts and his future as Sentinel's bitch - and Megatron shoots the shit out of Sentinel, saving Optimus' life. No ifs, ands, or buts. Then, Megatron asks Optimus for a truce and says "after all, what are you, without me?" - Optimus says "lets find out" and shoves his fucking axe into Megatron's head, and tears it off. killing him.
WHAT THE FUCK. Look - I undestand why Optimus might've done so - after all the Decepticons ass-fucked Chicago and killed a lot of people, and Megatron's motives for attacking Sentinel were pure self-interest. But it simply wasn't satisfying, and it made Optimus out to be a ruthless opportunist, and not heroic in the least.
What I wanted to see (since I had been spoilered for this part of the film, but not the shocking Megatron death) was Megatron and Optimus tag-team Sentinel. Instead I got Sentinel soundly defeat Optimus and then Megatron fucked him up from behind - and Optimus just fucking basically sneak attacks him?!
No. Didn't like this at all. I didn't want Megatron dead - but if he was going to die - not that way. I wanted a rousing fight, with energon axe versus flail.
Rosie Huntington-Whitley:- is no Megan Fox. I missed her.
Flaws in editing:- some stuff was clearly left on the cutting room floor. For one thing, after Starscream dies, Bumblebee saves Sam from a fall, and then in the next scene, all of a sudden Bumblebee and some other Autobots are captured. Huh? How? What the?
Another example - Megatron is just sitting around whilst the fight between Sentinel and Optimus goes on? Why? I can't help but think that the part in the comic was cut - i.e. that Sentinel gives Megatron a beatdown and Megatron decides to sit and be resigned to his fate. There's a little of that, but not enough to explain what he's doing. Speaking of which:-
Not enough Megatron:- He was wasted. Wanted more of him.
Skyscraper scene:- was overlong. Should've just started with Shockwave & the Driller, and left it at that.
Pacing:- action is crammed in all at the end, virtually. Would've liked a more even spread.
All in all, I give it a solid 3.5/5 stars. Would've rated it higher, if not my for my biggest single dislike.