I got that email also. I'm not sure that I feel good about getting an incomplete product and having to regularly update until (if) it ever gets completed. Reading the developer's blog it doesn't sound like it's at a playable level for the whole game. Looks like a lot of graphics assets, the intro and cut scene animations and the strafing part.
I hope that once (if ever) it is completed they will at least give us access to disk images for the final build. I, obviously, have no idea if they will be in business or have the update servers running the day after they complete the program. If I ever have to reinstall I'll be SOL. Not very cool, to say the least.
At least I got Defender a few months ago and it's pretty nice. If Wings does eventually get completed and at least to the same quality I'll be satisfied. Not particularly happy after all this time, but satisfied.