I’d like to report that the port of my project to TypeScript has been a success, so far the issues encountered have been minimal.  One issue I did bump into recently was due to a typo on my part.  I had used a variable in a small method as both a string and number at different points, like so

var x = parseInt(somestring);

...

x = x.toString();

During the conversion to TypeScript, I resolved the type errors caused by this by creating a string and a numeric variable like so

var xn : number = parseInt(somestring);

...

var xs:string = xs.toString();

but notice the typo, I did xs.toString() and assigned it to xs itself, not xn.toString().  This does not cause any compilation errors in TypeScript, but the code is essentially a guaranteed null reference error at run-time.  In my case it was a month before the little used method was executed.