Meteor is one of the most enjoyable tools I've worked with. The feeling of rapid progress one gets is very encouraging. It also works well and has built up a large community pretty quickly, meaning that answers and solutions to problems encountered can be found pretty easily. The package system (still undocumented) already has spawned a repository of community packages, which solve even more problems.
Not 1.0 yet, but seems very well-managed and like it's on the right track for great things.
The Meteor Development Group received a significant amount of funding to develop the framework further, and they've been upfront about the ways in which they plan to monetize it.