If you work at a store worth their salt they will work you to the bone. Especially in a large or high-volume store there is so much to do, so much to clean. A morning shift person will have the absolutely insanity of a morning rush, but an evening person should be expected to handle evening rushes with a limited staff as WELL as get the place spotless in what I believe is not a reasonable time. We could get the place clean by 10:45, all right--if we broke the health and corporate rules about when to tear things down. And of course if that was ever found out we were in deep. And if we went over 10:45 we were also in trouble. Management sometimes has some very unrealistic ideas about what the job actually entails and what rules and boundaries should go with that.
The pay in my state starts near minimum wage. The ceiling for a barista is $10/hr, which you hit when you've been there about five years. But tips help, and some high-volume affluent stores will have tips up to $4/hr.
There's also a tendency to have fanatical management. Other "kindly" corporations like Whole Foods have this too--the managers drink the Kool-Aid and worship the company. I once spoke with my manager because my schedule was being changed with less than 24 hours notice, and that was against state law. She got this crazed look in her eye and spat "Starbucks law goes above state law!" But that's only a tendency. There are some pretty cool managers out there. Mine was insane.
The customers are spoiled rotten so they also get kind of unreasonable about their Starbucks. They will stand there and demand that you make a drink five times because there's still foam on that latte and they said NO foam, not LIGHT foam. This is a business model of Starbucks': everyone is special, and we will bend the rules for everybody. And I've had people scream at me and call me a (b) and promise me that they would make me lose my job. I've also had stuff thrown at me. But, that's also just customer service.
These last few years Starbucks has been obsessed with selling, too. There's a lot of pressure on the staff to make sure people go home with $15 bags of coffee and sub-par espresso machines. It's hard to maintain the relationships they want us to maintain while trying to sell stuff.
Overall, if you can put up with the customers and the physical demand, and if benefits are more important than income, do it. It's rewarding in its own way. Wear insoles.