Running a restaurants is an absolute mess. Sadly, I think there are more bugs now than there were when Dine Out was originally released.
I decided to start a restaurant. First, I was unable to save outfits for the staff. It would take me into CAS, I would create an outfit, but then it would not save the outfits. There seemed to be no workaround for the issue, so I just gave up.
Once I got the restaurant up and running, my staff started having issues. During an 8 hour shift, my chef did not cook a single meal for the guests. I tried resetting her, moving around the cooking station and removed any objects that might be in the way. Nothing worked, so I just closed the restaurant.
The next day, I tried again. At first it was going great, but after a couple in-game hours, the chef just stopped cooking anything. I stopped accepting customers, and there were only 4 customers left to serve, but she just refused to serve them any food. Eventually, the customers got angry and left.
In addition to issues with the staff, the customers have all sorts of routing issues. They are constantly walking around the room, socializing with people across the room. I've even had customers leave their tables and go out for a jog. Sometimes I can't even tell who's been seated because everyone is standing around.
The Sim's team should really work on fixing up this pack, because it really is fun to run your own restaurant, but the numerous bugs and issues make it unpleasant and unplayable.