I'm not an engineer, but that's what it looks like to me.
1. It needs to do at least 40 MPH.
2. It needs a longer battery life
3. It needs an internal lock. A grove cut into the chasis that one can just put a bar from a bike rack into it, turn a key and it seals it to the rack.
Other than that, it'll sell for a while. Until it's registered and plated like a motorcycle, the hype will remain high. Perhaps there's some FReepers here that work for the postal system that can enlighten us about their experience with this in the future.