Should I first play the Decepticon campaign or the Autobot campaign and does it make any difference which one I play first?

Decepticon first, autobot second, The story goes in that order.

The story does go in order, however the beginning of the Autobot campaign sets you up with the plot.

You can play either, but I think it flows a bit better if you start decepticon and then go auto bot. The nice thing about the way they structure the game is that if you play the auto bot campaign then the decepticon campaign feels like a bit of a prequel. Cleverly structured on their part. :)

awesome,thanks guys