The interview process started with a very quick challenge problem. Then I was sent some hardware to hack for a second more challenging problem. The challenges themselves were interesting. However, all interaction with this company was awful. I had to send emails multiple times before anybody would respond. They were 15 mins late to a scheduled phone call (and only called me after I reminded them via email). The last email I sent them with my results from the second challenge has gone unanswered for two weeks so far. I was not able to fully complete the problem, but I documented my results in detail. Maybe they wrote me off because it wasn't finished, but I have no idea since they did not respond. I've had better experiences buying things on craigslist.