I'm comfortable without complete backwards compatibility. I expect the spec to continue to change in places. In an ideal world, that's the risk you take in using a Perl 6 implementation today: Larry reserves the right to change his mind on what 6.0.0 will be until he officially blesses what 6.0.0 will be.

I can deal with that.

What I don't consider "ready" or "usable" is a project which makes a big splash about how it's going to produce something "not complete, but ready for early adopters to begin using" which will be "refined and improved and released regularly", then slips its release for several months, makes a couple of releases, slips from monthly or so releases to "every three months", then undergoes yet another rewrite of core components, makes a half-hearted release of an abandoned line of code because "it's really about time we did another release", then slips more releases because that "just a minor refactoring, really!" is taking a long time and (unlike what the word "refactoring" means) produces quite a few regressions.

My business had a product we intended to release to actual clients about the time of Rakudo Star. We were all set to get things going around April last year. Then Rakudo Star slipped to July, and it was obvious that Rakudo Star wasn't of the quality we could use. (You might remember I did some measurement and performance work in Parrot around that time. Performance wasn't everything we'd hoped for, but we were counting on regular releases and about a 5% or 10% improvement every release—which we were able to produce—to be viable for early adopters just starting to explore the system.) I kept the project around until late December and then January of this year, when it became obvious that the nom rewrite (again, if you cause regressions when you refactor, you're not refactoring) would take far longer than claimed. (If you want to predict what other people will do, pay more attention to their history than their estimates.)

I was ready to scuttle the project then, but one of my business partners talked me into wait and see mode. (I appreciate the bitter irony that said partner wasn't even keen on starting the project, as I am the only one among us who was, but the opportunity cost of watching and waiting was minimal.)

That project's not going to happen in 2012. I've cut our losses. I don't know what of the existing product will be salvageable if Rakudo can get its act together. I don't know what will work if another implementation becomes viable.

Now then, someone go on and tell me yet again that "Perl 6 is usable right now!" because I was ready to ship a product with it almost a year and a half ago, and it's still not ready for that.