The number 1 critcal milestone for this release is the webpositive. No OS is worthwhile unless it has a good web browser.
Its pretty easy to argue that once there is a good web browser nothing else is really needed at this point. You could easily do just about everything on a computer on the web these days (well, maybe not EVERYTHING, but a LOT of things).
Overall its still fairly useless as a day-to-day operating system. Not because the base feels unstable, but because there aren't enough quality applications to make it useful. But, that was BeOS's problem 10 years ago as well.