The Steam Early Access page has similar disclaimers, such as "[DayZ] is a work in progress and therefore contains a variety of bugs. We strongly advise you not to buy and play the game at this stage unless you clearly understand what Early Access means and are interested in participating in the ongoing development cycle." Like that's going to scare us off.
There's a section on the Steam page that talks about the development roadmap -- drivable vehicles, wildlife, player-made constructions, user mods, and more are indeed planned. Here's the kicker, though: "We estimate that reaching Beta version with all key features present will take more than one year from current stage." Well, we've waited this long. What's another year (or three)?