two rides into my single speed (not fixie) career and i kinda like it.
there are drawbacks - firstly i'm unfit so it gets hard work on the uphill bits and secondly it still feels slightly alien to me as my thumbs look for shifters that aren't there but i'm certain that will pass.
the bonuses for me start with the feel of the thing, i can't describe it in any other way than it just feels 'right'.
to me, anything with settings gives you something to faff about with and detracts from the overall experience. The best example of this i can come up with is hunting. I do a lot of shooting and some people i know will go out fox shooting with range finders, night vision bino's, their rifle, a lamp, different bullets for different ranges and loads of random stuff that isn't essential. others will go out at dusk with a shotgun, maglite & a handful of heavy cartridges and shoot just as many! bikes, can translate to the same thing. on my orange, I tend to change the damping on my forks depending on the terrain, i seem to be forever changing gear, altering seat height and second guessing that something is wrong if the chain doesn't jump immediately into the next gear. on the single, I had none of these thoughts I simply sat down and pedalled.
it might be fashionable at the moment but i like it so i'm gonna keep riding it!