I find it interesting to get new content in updates. 'Course, with minecraft every time they updated it caused about everything to be outdated and it's extremely frustrating for multiplayer servers :X
I thought about getting Arma 2 and the DayZ mod, but then I saw some preview videos for the standalone. It looks pretty darn amazing. I figured I'd hold off on buying anything DayZ until the standalone is released.
Release it complete, and then release content afterwards. Rather than printing a list of promises, and then saying "we'll get to those later"