Hardly believe this qualifies as a "con", but you should come into a start up environment with your eyes open. There will be days that you'll be required to stay later than five, but I believe you'll be hard pressed to find work that is this rewarding and willing to compensate you for your time all while getting you out the door on time. THAT being said, I believe Keeper values their employees time more than other places I have been and the culture is built on making sure the work stays fresh, fun, and rarely overwhelming.