Although I feel like we have been successful, there have been so many business and technical challenges that I'm quite sure that we would not try this one again if we had to go back knowing what we do now.

It's a two-sided marketplace, which means we had the chicken and egg problem and the network problem. To add on to it, we had to figure out how to build trust using a medium (Internet) that has been traditionally untrusted.

We had to figure out how to scale customer service for a business where we quickly found out that people expect good customer service. The Google model for support wasn't working.

Further, the field is littered with the corpses of, sometimes well-funded, ventures that have failed in the same space.

And finally, our initial marketing plan involved boots on the ground, kind of like a political campaign (all the founders met in DC on a political campaign). That one failed quickly.

The latest, hardest part is scaling the matching engine without using humans. Not sure I'm at liberty to say exactly how we solved that.