It will have at best all Chrome users, and this probably be about 20-30% even in a couple of years, so only a couple of developers will really use it for real. Just now how GWT now is used.
What are benefits of Dart rally?
And that's pretty all of it.
Really, there is nothing really impressive in this new language. This is mix of some other OOP languages. Nothing new. I can tell that this is boring.
Types - JSEngines guesses types, and if only programmer stick to one type in one variable it will work really fast on new VM, this isn't really a issue here. In optimization faze it can be easily done without types in language.
As I see It now, Dart will probably end like Go for servers. Anyone really use it for real. Somebody on the whole world for sure, but it don't catch up.
Consider running the same code on server and client. Node has done that, nothing new. It would be nice but not really that important.
"at least for now" - time to explain this.
Some background: http://www.mikedaddy.com/archives/2011/09/22/oracle-sues-google-over-android-and-java.html
Oracle is not happy seeing Java on Android, especially because they get Java and make it only for them. Java was supposed to work pretty the same on all platforms, Google ignored it and implement only a subset of it. In my opinion Oracle should win it.
What Google want is really new language that is very similar to Java, to be familiar to Java developers. Language bring all sweet sugar to developers from Java. This is all they want from at least a couple of years, and now are waiting to see in Java 8.
Read the post from conference: http://dartinside.com/2011/live-from-dart-launch/
Do You all get it now?