I've got a couple of big trips coming up and will be putting it through its paces. The practical side of things is that any design issues on the D600 will be new problems - not the same old ones again.
I was a very early owner of the D800E. The images it produced were so much better than any other camera I owned that it was well worth it. I do have the left focus point issue, but understanding the problem makes it largely a non-issue.
I have a very specific need for the D600 - maybe a bit of an unusual need since I plan to convert it to IR. My understanding is there will be excellent availability of the D600 and the initial shipments are right after the announcement. My guess is that Nikon has stepped up testing to avoid issues.
Every camera has some sort of issue - and its not just Nikon. And its not just cameras as Apple has its share of issues. I do think there is merit in waiting for the bugs to be identified and worked out, but it sure is fun to get an early release of these new cameras. Like other products, you have to be willing to accept minor hiccups if you are an early buyer.