It took a week but finally had a chance to take one for a spin last night, and then rode in to work this morning on one.

My impressions:
A little unstable with weight on the bars
The bar basket is too small even for my modest messenger bag with a Macbook Air inside
The gearing is too low. I used the lowest gear going up the Manhattan bridge, but I was trying not to get sweaty on a humid day. (it didn't work!)
They otherwise ride pretty nicely.

Since I already paid I guess I'll use it fairly frequently, but it won't replace my regular bikes (3 road, 2mtbs).