I, like you, was extremely nervous of upgrading to a D800. I have to say it's without any doubt it's the best Nikon I've ever bought. I said that about the D700, but the D800 exceeded all my expectations.
I've had no problems although I would echo Ken when he says to buy a good book. I have both Darrell's book and Thom Hogan's truly wonderful guide to the D800. Both give valuable information on how to achieve the very best out of the camera.
I would forget now all the negative talk as I have, that's history for most although those who suffered may think differently of course.