I worked at Smashburger part-time (Less than a year)
The pay was decent, the crew I worked with was a lot of fun to be a round, the job was self-explanatory.
My hours were always changing each week, one week I'd work 10 hours, another I'd work 20. The managers did a really bad job of making sure food got to customers by continuously bumping items that hadn't been delivered yet. When the items were bumped, they disappeared from screens in the kitchen, so the food was never made.
Advice to Management
Wait to bump food until after it's delivered so the customers aren't waiting an hour for their burgers that were never made so you don't have to keep handing out vouchers to upset customers.