I've played DayZ a year ago, and it was nice. The explosion of survival games, as I see it is scratching a long-extant itch, much like isometric RPGs, puzzle platformers and space shooters, which we're seeing coming out of the woodwork now.
They don't really do much for me, to be honest, as much as I like them in theory. The chief problem I see with DayZ and Rust is that 'survival' is just one way to look at it. By and large, they are deathmatches, except some people are not trying to 'win'. It's a genre I feel is still 'in progress'.