Meteor blurs the line between client and server, and actually takes advantage of the fact that it’s all Javascript. Methods are functions that can be invoked from the client, the server, or both. With Meteor, you’re actually sharing big chunks of code between the client and server. While it’s possible to do something similar using ember/node, it’s difficult enough that most people don’t do it. This really changes how you build things. More client/server sharing = less code = less work and fewer errors.
Yes it is, but I'll waiting for a 1.0 release before I'll take a serious look myself...