My first reaction was, "They're going to fuck this up and ruin my childhood!"
Then I realised that I still have my old Transformers somewhere, and while I have them, I can relive the original G1 goodness in all its poorly-animated glory. This movie is essentially a chance to go and, as someone else said, watch some massive robots fuck each other up. I'm all for it.
Also, Optimus Prime. Didn't know how he'd translate to a long-nose truck with flames down the side, but it looks pretty fucking sweet.