Overall, positive experience. The problem they're attempting to address is very compelling. If they overcome challenges, it will serve the greater good. Everyone I spoke with was interesting and had depth. I could easily enjoy collaborating with them on a technical problem, hanging with after work for a beer or pursuing some non-work hobby. The take-home exercise was a lot of fun, and not too time-consuming. I also spent a lot of time with the online product demo. Unfortunately for me, I am not great at the performance art of whiteboard programming. The only area of improvement was HR's follow-through. I have the impression that the tool they use for applicant tracking is dropping responses, because if my reply went through that system, I'd not receive a response, whereas if I manually added someone to the Cc, it was fine.