And it can't go uphill...
From the FAQ:
How well does Halfbike handles hills?
Riding uphill is alright as long as it is a gentle slope. Halfbike isn't really made for steep hills so if it gets too steep you may have to push.
I also noticed two different frame designs, one of which looks hard to get U-lock through, and the other may be impossible. The FAQ suggests using an 'ordinary cable-lock', which doesn't sound very safe.
You certainly wouldn't want to lock $1,000 up with a cable lock.