I've ridden the Simano Nexus 8 and Alfine 8 on my primary transportation bicycles for the past 6 years, and am extremely pleased with my experience.
My wife's bike has the Alfine hub/hydraulic disc combo and it is a very nice setup. Excellent quality all around.
I'll add another note regarding wheel removal - it is EASY, once you know how to do it. It is daunting to do the first time, because it is so different than a derailleur setup. What I've found is that I actually find it easier to do than with a derailleur - there's no navigating around a pulley or tussling with the springy derailleur to align things before slipping the wheel into/out of the dropouts.
So, follow the advice posted thus far and get your hands on it to get comfy with it.
I highly recommend having a 2mm hex key (or I use a 6" length of an old spoke) to insert into the hole (that shimano has provided for this purpose) to rotate the mechanism, making the cable process ridiculously easy. Takes me 5 seconds or less to remove or re-install the cable.
As far as reliability, once the initial indexing is set up properly, it is a spectacular system that will give you many, many miles of trouble free service (or least, it has in my experience).