01. The movie was far too focused on humans, despite being titled "Transformers".
01a. Too many separate plot lines revolving around humans: a) Sam and his glasses being sought by the Decepticons, plus the romantic angle with Mikaela that no-one cared about, plus family stupidity. b) Code-breaker girl and friends who never really did much of anything in regards to the signal (summary: "wow a signal! what is it? we don't know. oh, there's giant robots we see now. call for a military strike.") c) Military dudes running away in desert then finally ending up back home to fight some more, because they were too late to report a hostile robot. The rest of the world already knew by the time they got home. Note that plot lines b and c basically fizzled out half-way through, amounting to 'not much'.
01b. The number of lines each transformer had was questionably short. I challenge everyone re-watching the movie to take the time to count the lines uttered by each transformer, then determine how many of those were even substantive. Most were short, one-line dialog with little import. I found that Autobots averaged between 15-25 lines each, many of which were short, pointless banter or battle instructions like "Run!". The Decepticons were far worse off however. Megatron had over 20 lines, most being battle-banter of little substance. Frenzy had the next highest number of lines amongst the Decepticons, except they were all subtitled due to being audibly unintelligible. Barricade had the third highest, but most embarrassingly stupid ("Are you username ladiesman###?!".... twice.) lines. All other Decepticons had a mere three or LESS lines.
02. Bad visual experience in many instances of robot combat.
02a. the much-loathed shaky-camera effect.
02b. the near indistinguishability between most of the Transformers in their robot forms, outside of Optimus and Bumblebee who had enough color beyond silver/gray to appear notably different. This, combined with shakey-cam, made it really hard to follow a lot of the robot battle scenes.
03a. Every machine brought to life by the cube was immediately violent (basically, a Decepticon).
03b. Soldier uses motorcycle to initiate a completely controlled slide across pavement for upwards of 30-50 feet on his back and stands up with no horrible tearing of clothing or flesh to be seen.
03c. Making out with your girl on top of your new best friend, while HIS friends watch is somehow acceptable if they're all robots?
03d. The sheer stupidity of toilet humor (dog leaks on robot, robot leaks on human).
So what else do you guys have to say about it? I started with bad points, but feel free to offer up good points if you can explain why they're good with reasonable logic and intellect.