It's got the simplicity of a singlespeed with the convenience of gears. Inputs on application and models are appreciated. Pros and cons?
No, it does NOT have the simplicity of a singlespeed: you get to think about shifting gears. In fact, it has absolutely nothing in common with a singlespeed, where you get to mash a bit uphill, but never think about gears: if you want to go faster, you just pedal faster, that's it.
That said: yes, I do have a gear hub bike, but don't use it, and today, in fact, I'll be selling it. I have a Nexus 8 with Nexave rollerbrakes on it. I can only say prizes about this setup. Very sturdy, durable, simple to maintain. As long as you remember that you DON'T need to remove both the shifting cable AND the brake cable, when changing tires. And, the rollerbrake is just fantastic, works the same in all weather conditions, no pads to replace, no rims to clean... If there was one thing from this bike I'd want to keep (if that was possible), it would be the rollerbrake.
I also cycled on a SRAM S7 with coaster brake. Very nice, too, but the bulging clickbox, prone to being hit and smashed, as well as the plastic indexing thingy (you know, that red plastic thingy that goes into the clickbox) that is way, waaaayyyy too sensitive and easily breaks.
The SRAM S7 and the Shimano Nexus 8 have about the same ratio of gears: about 300%.