Saw it last night.
First half was good (in terms of accepting TF for what it is), audience laughed, groaned (red strawberry laces), it didn't take itself too seriously - as a film about giant english speaking robots who can be swayed with emotional arguments, with 2 arms/legs and mouths has to be - but then the 2nd half was everything that was wrong with TF2, an endless set of explosions, plot going walkabout, characters disappearing never to be seen again and basically being about 3 times as long as it needed to be. I don't think the audience made a peep in the last act, and by the time they'd started the big fight my interest levels were waning.
Pity really. As most have said, better than no2 but no1 still stands out as being the best due to the plot/advancement of plot being coherent-ish, the action scenes not being drawn out longer than they need to be and generally being less crap.