I thought the plot was too uneventful. The action and fighting's fine, but it's riding on a drowsy plot. Too bad because the art is excellent. Definitely buying this one when it comes out in bluray or whatever.
Fallen WAS a bit slow to get going, but there was a very definitive plot moving it forward which it astonishes me to see the critics bash it for not having one at all (although here is where the length worked against it somewhat. I think if it had been a half hour shorter the plot would have been clearer). Even if they left it the same length the story may have worked better if they brought Jetfire and the history of the Fallen in a little earlier in the film, as that's where the plot REALLY got going. It actually was a VERY Indy-esque treasure hunt/chase film. Just substitute the Nazis for Decepticons and the Lost Ark for the Matrix of Leadership.
One place where I think the critics are being unfair is that Fallen DEFINITELY felt like it's meant to be watched with the first movie, and not as a stand-alone film. If you look at it from that perspective the seeming lack of character development makes better sense, because that development is being spanned across TWO films, not just one.
They COULD have been a little more original with the Decepticon lineup, as they duplicated a lot of the Constructicons throughout the film:
According to Wikipedia, Devastator in the movie was formed by: Mixmaster, Scavenger, Scrapper, Hightower, Overload, Longhaul and Rampage (yellow). However they ALSO duplicated Mixmaster for a Decepticon killed by Jetfire, Demolisher--who was killed by Optimus in Shanghai--was identical to Scavanger, a second Scrapper was killed by the other Constructicons to resurrect Megatron, another Longhaul is killed by the US military during the final battle, and Rampage (red) is killed by Bumblebee. I guess it saved on production time to just "palette swap" the Constructicons to create more enemies, (they also duplicated Blackout from the first movie as Grindor in the 3v1 against Optimus) but there's so many characters they COULD have drawn from instead.
I did like getting to finally see Megatron and Starscream bickering. That, and Starscream telling Megatron at the end "It's not cowardice to make a strategic retreat" as an excuse to save his own bellybutton REALLY took me back.
And dammit, where the hell is Prowl?! I'm REALLY wanting to see him kick Barricade's bellybutton in a Black-and-White battle to the death!