I agree wholeheartedly with your review.
My take on the film -
Biggest joy: the loyalty to the feeling of the cartoon (Jazz was deliciously over the top, and Starscream and Megatron even got a one-line reference to their bizarre relationship in!)
Biggest letdown: Megatron turned into something useful; it would have been so much better if he'd turned into a gun someone else had to use - plus he looked too cool and modern.
Biggest shock: transformers, perverts in disguise! They traveled across the galaxy, apparently to save us from destruction, indulge in water sports, and set up a dogging club. Ewwwwww. :)

I just don't have the Transformers Thang, I can't tell whether I'm too young, too old, too girl, or too what but I just missed it somehow. I have every other geek going but not Transformers.
(Slightly worried about Jen's biggest shock above)

The dogging at the end was disturbing, especially with the implied human-human-robot threesome, but far and away the most shocking bit was the piss sequence. I've never seen a golden shower scene in a 12A film before and I sincerely doubt I'll do so again.

Are you messing with me?!! I thought Jen was kidding!

Nope. He pulls off his fuel cap off of his groin and sprays the arrogant secret service man while Optimus Prime chides him with a playful tone in his voice, "Bumblebee, stop lubricating on him!"

And there can be no doubt as to the lubricant/pee connection, as earlier in the film, the family pet of the main human pees on Ironhide's leg, and Ironhide says "It's spilled lubricant on me."

It came as quite a shock to me too, I can tell you. I think the vague in-character justification for Bumblebee's action is because his speech unit has been damaged so he can't speak. However, as we know he has an alternative method of communication (talking through his in-car stereo, used earlier in the film), the peeing on a guy is made an even more powerful statement. What isn't made clear in the film, though, is if it is harmless oil, or, as the viscosity and colouration of the liquid seemed to suggest, is actually petrol, in which case the gesture takes on a far more threatening approach.

It also means that even if Megatron was on fire, no transformer would piss on him to put him out. :)

The cinematography on the piss sequence is pretty good, actually. You have this helpless man in the foreground while Bumblebee is towering behind him, letting off a big arc of robot piss all over him. You can tell they put a lot of care and attention into that shot.

You know in Final Fantasy Games when the hero has a response beyond the power of mere words and a little speech bubble appears containing "..." Well I'm doing that now.