The shifts can become quite tiring, especially at closing times: You know at what time you start but you will never know at what time you finish, as the staff cannot leave the shop until it is perfectly presentable for the next day.
The rota are available with very little time in advance, so arranging plans for your personal life is almost impossible. Furthermore, this shifts can easily change from one day to another and you have to cope with it, no matter what your plans were.
The salary is not excellent
It is a busy environment where you have to be ready to start rushing as soon as you start your shift. Everybody looks very stressed all the time and there are always thousands of things to do, so people with anxiety or not very energetic can find this circumstances quite unbearable.