I have one, and I am very happy with it. It is more robust, gearchanges are far easier, and there is less maintenance. I think there can be no argument about its superiority. I am a member of the Dutch cycle touring club, and I think some 75% if their new bikes have the speedhub. I have not yet heard anyone regretting their purchase.
The biggest and for a touring bike really only serious disadvantage is their price. If I was on a limited budget I would prefer a gorgeous frame with derailleurs to a mediocre frame with a Rohloff hub. The bike's feeling is in the frame, after all. In similar vein, I would not replace a good bike with a Rohloff bike. Get one if you are about to buy a new one, but don't if you do not need a new bike.
Willem