I've been using nodejs exclusively lately in work (html5 edu games on top of web apps), and prototyping got really easy. It's not using meteor though, but express (plus jade and stylus) so still not riding fully the front end mvc wagon. The scope of our audience is too broad. Plus on professional work i tend to be minimalistic, so rails-like gargantuan approach isn't my cup of tea (though you could argue you can shift it towards customizability if you know what you're doing).
Meteor for the most part have made huge leaps in their recent updates. They don't claim to be production ready yet, but some groups have already made the attempt. Hosting and setup is another factor, and we should see more support in the months to come. Meteor can make developing one page apps feel like you're still doing the traditional, and they made great work in adapting it to transitioning devs.
Another framework that sticks to javascript's strengths but tides on the full stack is derby, older than meteor and has less hype but is also worth checking out.
Sent from my iPad, sorry for teh typos