I briefly got a chance to play with it, but it was more of a *demo* situation. One of the coolest things about it, IMHO, is the manner in which it farms out compilations automatically. Java is one of the many supported languages, but I only got to look at Objective-C. It has all of the usual features you would get with BBEdit, SlickEdit, or Eclipse, and also the always intuitive apple interface.
Of course, it is also supposed to integrate very well with WebObjects. So if you're an apple shop, or just apple friendly, it should provide significant productivity enhancemnets