One of the difficulties in getting a new computer language accepted by a wider audience is that there is doubt that it is real. Is it a toy language that just proves a concept or can it do real work?
Interestingly, the demos only work out of the box on Chrome - I failed to get any of them working under the latest Firefox or IE9. Let us know if you succeed.
At the moment the code is a first port and there are lots of features of the Dart language it doesn't make use of. The team hopes to improve it in the coming months and make it more Dart-like.