I think it's great, and I'm looking for a city mixte for my girlfriend, and was even thinking of going 650b on the build. I love everything about this one, but I think the 20" size might be too much of a strain. My girlfriend is around 5'8"/9", and can safely sit on my 58cm frames, so I think it's too short for any use I'd have for it -- or else I'd send you an offer right now.
Here are a couple other swooped-stay 650b french mixtes, of course all of these are actually IN Paris...
http://veloflaneur.wordpress.com/201...ixte-parisian/
Such beautiful bikes...