Personally, I'd enjoy that "unplayable" version for what it is, but I can see how some other users may not realize that you're still in the middle of fixing all of the bugs for such a major change and end up spamming the boards with useless posts.
Of course, you could just create a bug topic for it, post saying that you're not going to check there because it's an alpha, but suggest people post reports there in the meantime.
As long as it's able to start up without crashing, it would build anticipation even more, however, and people would begin clamoring for more of your sweet, delicious... code.
But overall, I don't know. It might pay to release a bug-filled version sooner rather than later. There might be bugs in it already that you haven't expected that will still be there later. Having a list of prediscovered bugs for when you feel that 1.3 is finished would allow users to try and replicate the bugs they found previously. It would help the bug-fixing process a bit in the long run.