I just bought one of these second-hand, a 2014 model in lovely olive green. I almost immediately trashed the left crank pedal thread by not doing the pedal up tight enough, so I now have a 170mm Sturmey Archer crankset on it, which looks pretty much identical to the stock version.
I absolutely love it, so much so that my next bike may well be a more "road" single speed such as the Genesis Flyer, as opposed to my original plan that n+1 should be a modern geared road bike (the only other bike I have is a late 70's Carlton Corsair 10-speed). I see this year's Flyer will be £100 less than the 2014 model, and in a "cherry bomb" colour which I'm hoping means chrome finishing kit.
The 42x18 gearing seems to make it very eager, as I've seen mentioned in reviews. It's ideal for a shortish commute or a commute with a few hills, as I think on the flat and down slight downhills I could use something higher geared to get a bit more speed. I'm lucky to get 20mph on the flat, when I feel like I'm sprinting like Sir Chris.
It seems a shame to change the gearing though, I really enjoy its personality now. Hence the need for n+1! My wife doesn't understand this logic, seems reasonable enough to me.