I am a full-service shopper and despite what a lot of the negative reviews say, I have had no trouble getting the hours I want/need. They take your availability and then make a schedule but if you don't get the hours you want or you need to edit them, you can always pick up or drop shifts. I was scheduled for about 10 hours/week but worked closer to 25-30 after picking up shifts. Pay is good (thanks to tips) as long as you have a busy day. I have made anywhere from $14-$22 an hour depending on the day.
I will say that I don't think this is a great job for long-term full-time employment. It's good as a part-time job or to hold you over during job transitions.
Also, despite what others have said, you can take a 20 minute unpaid break. There is an option on the app to do so.