Square was great. During my time there, the company doubled in size, tripled in valuation, built a plethora of new products, and experienced all the chapters in the adolescence of a successful startup. Everyone was intelligent, most of them treated their coworkers well, and nearly all felt a sense of camaraderie and loyalty to the company as a whole. Left for YC, but if I had to do it all again, I might choose to stay! Those were good times.