My first reaction to Dart was "jeez, yet another c-like, java[script] clone". I hated it, I want a world without stupid braces and semicolons. It doesn't seem to bring anything new to the table and it looks exactly like java, c#, javascript, etc... and exactly for the same reasons (to be familiar for the average programmer). Syntactically, it's dull and unexciting. However, on a second thought, I changed my mind a bit. Like it or not, it has to be this way to gain wide adoption and, indeed, anyone with experience in java or javascript can get productive in no time with Dart. But what's really interesting is the snaphot feature. Dart will load in milisecons in the browser, making startup times irrelevant. It's also designed with performance in mind, and it will have some features that will make it ideal for large code basis and team work.
As for its boring syntax, this won't be a problem. Coffeescript demonstrated that you can target a messy language and make it beatiful and fun. Dart already has a "transpiler" for compiling it down to javascript. If Dart becomes a good compilation target (and it looks so), people will start wrting their own transpilers targeting Dart. The best of both worlds. As for the concerns about the null chance of other browsers adopting Dart, this is a battle they can't win. Dart will run everywhere, either on its own VM or compiled to javascript. And it will lead to a situation where new applications run on every browser, but "work best on Chrome". How long will the other vendors keep on pushing a mediocre, substandard language such as javascript when Dart is already making developers lives easier, and applications faster and better?