There's much support for Rohloffs and they are nifty and fun. It seems many believe they are absolutely dependable. They can fail just like anything else that is complex and man-made. In a post I made several years ago I documented a number of folks who experienced failure while touring. You can see links to these in post 17 of this thread:

http://www.bikeforums.net/showthread.php/513123

Other thoughts about limitations with Rohloffs can be found in this thread:

http://www.bikeforums.net/showthread.php/556908

There are also many who speak of the virtues of the hub in those posts.

Cost seems to be the primary limitation; one could replace a derailleur, rear hub, and cassette many times for the cost of a Rohloff. But if one has the Rohloff bug, and it seems interesting, then go for it!