This is a brilliant tool especially if you are from the OO, type safe world as many of us are. Now these is nothing wrong with pure JS as we have produced some impressive products with it. My latest project was working on a video player where the UI is entirely in pure JS. This effort was made much easier with use of the Module Pattern, RequireJS and Underscore. The point is that JS is a language that was developed in 1994 in 10 days. Good grief Smalltalk took 9 years! I am sure Typescript development effort is measured in person years. JS languished for years but in the last 2-3 we seen a remarkable steps forward in the tooling. This is what is really helping as so much time is wasted in JS with things like typos.
Anders is one of the great minds in this business and I applaud his efforts here. I really like the integration with Visual Studio including Express. It appears that Anders will evolve this product along industry standards and that is critical.
Like everything this is not a solution for all but for one who has been in the trenches with JS I embrace a tool like this that can help in so many ways.
I also feel is too bad that people cannot share opinions in a professional manner as I truely believe they do not realize that it diminishes the point they are trying to make.