It's 100% ready for production. Joyent runs a very large platform on SmartOS, and I can verify that at OmniTI we had the vast majority of our hosted customers

It's 100% ready for production. Joyent runs a very large platform on SmartOS, and I can verify that at OmniTI we had the vast majority of our hosted customers running on OmniOS. I worked there for a bit over three years, starting just before the initial betas of OmniOS and watched as systems migrated from Solaris 10 to OmniOS without any major issues. (I say "watched" because I was in dev rather than ops, but I don't recall any inordinate grumbling.)