I got the dev kit and, to be completely honest, it's a little wonky for "WASD" games. Some people take to it like a duck to water, but for me there was definitely some wobbly head syndrome and inner ear stuff going on. The immersion factor is a given, but I think it'll take a while before it's something that you want to wear for play session lasting even a few hours...It's awesome new tech that seems like a great fit for an MMO. It's not a priority, but I'd love to see it in action and the device gets universal praise. Valve is doing pretty good with making it easy to integrate, too.
I would say wait until the consumer version is released, and maybe check back then. There's still a lot of research being done on how to minimize eye strain, and include proper calibration tools for eye separation, etc.