Let me put it this way:
I've wanted an iPod for eons. Well, not literally, but it seems that way. About a week and a half ago, I got a new 4G 40GB 'pod, and it was beautiful. Changed the way I listen to audio books more than anything - I like listening to them on my commute, but burning CDs was a pain in the butt. The iPod changed all of that. It was nirvana.
However, at the moment, there is a box sitting on my desk which arrived today. Its purpose? To return my iPod back to be fixed. Why? It has spontaneously rebooted three times in ten days whilst playing music or audio books. Sometimes, when in its dock, it decides that it cannot be disconnected, even though iTunes is done with it, and in fact even at times when iTunes isn't even on - it just, out of nowhere, decides that it's synching.
In maybe two or three weeks, I'll get mine back. No next-day service on these things.
And, in addition, there aren't any or at least not many cases out there for the 4Gs yet (but that'll change soon).
So, I'll leave it up to you, but, if it were me, I'd wait.