You can take a look here: http://simonpai.github.io/2014/09/03/quire-building-with-dar...
Right now we use Dart for the desktop browser optimized version of Blossom and for a bunch of command line/build tools to manage things like building, testing, release tagging and deployment.
We're super happy with the language and platform. DartPad (https://dartpad.dartlang.org/) is a great way to get a feeling for the tool support of Dart (semantic autocompletion, helpful warnings etc).
I'll write more about Dart and how we use it at Blossom (https://www.blossom.co) going forward.
I have read Quire's (http://www.quire.io) article on using Dart to develop their application and it seemed very positive. I just wondered about your experience.