I haven't had much time to play with TypeScript, but I have gone it installed and I've gone through some samples.  I think it's a great idea and will really help a lot ... I've worked on some pretty big web applications that were written entirely in JS before and during migration from ASP to ASP.NET, and it was a nightmare, but TypeScript would have changed the game.  It would have actually made sense to never migrate to ASP.NET at all if TypeScript had existed then.  The only reason people seem to have a bad reaction to it is because of Dart/CoffeeScript and all that and they are definitely not the same thing.  If TS had of been available a year or two ago, I think no one would be talking about CoffeeScript or Dart.  The tooling will be the key to victory for TS.  Why would anyone with a lot of JS and VS2012 not use TypeScript?