Building a point of sale was much more humbling than the website. It was much more UX intense than the website. While the requirements were loose, the POS was business facing, so the clients were more critical. There were major bugs I wouldn't find til deployment, admin features like menu editing kicked my butt, and the printer setup was a nightmare. My lowest point was sitting in the back of the restaurant on their grand opening on a Friday night, trying to connect a USB thermal printer to a raspberry pi running cups, a dev python server, and noip.com's script, so that it could receive PDF files of the receipts through an open port on the router. It's incredible it even worked. Even more disappointing is that they ended up not seriously using the POS system until weeks after it was ready.