I think it's just too expensive and specialist. If you go for the alfine hub version it's getting on for 3k. For a lot less money I'd rather have a Birdy.
I've not ridden a Birdy but I've always liked the look of them. There used to be a chap who got the same train as me who had a Bike Friday and they look rather spiffing too, but I've never ridden one of those either.
I have ridden an Airnimal Joey and very much liked it - it rides like a proper bike. But I don't really consider it a true folder - you could get away with taking it on the train for a mixed commute, but it's far from convenient compared to the standard commuter choices (most of the ones I see on the train these days are Brompton or Btwin).
I've ridden the Hummingbird and loved it. I would get one, if I could afford it. In fact, if money were no object, I'd get the Hummingbird e-bike, which is truly awesome (even with the motor it's lighter than a Superlight Brompton, which is why it accelerates like a rocket).
M'colleague has ridden both the Atto and the Hummingbird - I shall have to ask him how they compare.
The Atto looks like its folded state isn't as compact as the Hummingbird (which is taller and longer than the Brompton when folded, but also much narrower). The Hummingbird has a Brompton-style folding rear triangle, but unlike the Brompton it pivots around the bottom bracket so doesn't need a chain tensioner.