I'm currently working on a big Angular app that is about to move into production (although it's not to be something that's widely used in public) - we have found that Angular causes everything to be structured in a nicely organized fashion overall. This app is not structured perfectly by any means either, due to bad design on some of our pre-existing code base.
From what I understand, big Ember projects have turned out well for Ember devs - I can confidently say that I feel the same way about big Angular apps. I have built several big ones, including an online assessment platform (frontend by myself) and an online assessment platform/management system (with a team of ~10, 3 of us on frontend).
From my experience, the Angular team has thought things out on a high level, which I greatly appreciate. They are big consumers of their own product, as Angular is used quite a bit with Google's own sites - here is an example of an Angular app, with Angular being used to implement parallax scrolling (and probably more): http://www.google.com/nexus/7/
From reading the Ember discussion lists I get the strong sense that the core team is willing to make difficult breaks, but that they really try to only do it when it's absolutely necessary for the long-term robustness of the platform. A lot of thought seems to go into which problems are getting solved now, which are put off til later, and which interfaces get torn out and rewritten.
I just spent several weeks upgrading my app from the earlier Ember RCs to Ember 1.0 and the latest Ember-data, and while quite painful, I feel good about it because I don't think the core team made those changes lightly. My sense is they are looking out for us.