If they want this to be the next Django/Rails/Express/whatever, where a large and enthusiastic community both uses and develops the product then the answer is fairly clear: No, this is not a suitable license.
If their idea is that it's an nominally open source project where all control and most development takes place inside the originating company, and the community mostly just pays license fees then: Sure, it's a great license.
Longer clarification: Django is licensed under BSD, Rails and Express under MIT. Why? Because these licenses allow me to use these frameworks for my own webapps, without making the entire client/server code base available. I can toss together a Rails-based contacts manager, or a Django-based todo list app, and let people sign up, and even charge a monthly fee, and NOT have to give the code to the entire app out.
Someone else linked to Sencha's discussion of the GPL and JS webapps, and it's highly relevant: http://www.sencha.com/legal/open-source-faq/
In short, as long as Meteor is under the GPL, I can use the framework for free, but I cannot let anyone use a webapp I create with it without giving away all the source code. Which means that I'm very unlikely to actually install and try Meteor on my next project. My choices are basically "ignore Meteor" and "pay a license fee to the devs". Meteor is awesome, and probably well worth the license fee (whatever it might be), but it's fairly obvious that this is a huge limitation on the frameworks potential for adoption.
(It's worth noting that both Django and Rails were actually developed for a project, and then released under permissive licenses, because the framework wasn't the product, and the dev teams didn't need to try and monetize it. Meteor is the product, and the dev team does need to monetize it. And, again, Meteor looks awesome! So I can fully understand why they chose GPL, and I fully support that choice! But it is worth noting the consequences of that.)