The only quibble I can find with the book is that since you've said, experience with building web apps is not necessary, I think you might want to dedicate a chapter to teaching that. I remember learning web apps for the first time, and the only time it actually clicked into place was when the whole concept of how pieces come together was shown. Nothing fancy. I learned web apps using udacity's course so that should give an idea of how simple a chapter it should be. I think it would really help given how much magic seems to be going on at any time with Meteor.
Thanks again for this. Kudos and keep up the good work