Growing pains, that's all.

They've really done a lot of work. The jump from 0.6.4 to 0.6.5 was 775 commits. Wow. We're seeing concepts being fleshed out, they'll be refactored and strengthen in time. The team seems to be fully focused on 1.0.

Scalability is still a big concern, but it's only a problem you can be so lucky too have.

Meteor still needs to improve code structure, there's no common architectural pattern yet (just some lose guide lines). In my opinion, it would be a benefit. Meteor is still in its infancy and a developer is left to their own devices, rather then common sharable patterns. Rails does this well with the plethora of use-case strengthened API design, a benefit of it's maturity. Meteor will get there.