There's certainly reason for caution, given the history of Rev. 1 products. On the other hand, I've had three iMacs -- G4 (lamp), G5 and now 24" Intel -- that were all first run and none of which had any hardware issues. Of course, after typing that, my screen will immediately catch fire.
I love the new 27-inchers and want one, but also hope my current machine will go another 18 months or so, as I think all the new models are really missing is USB 3.0 and wonder if the next turn will bring that.