Although the company has a lot of employees, it is still pretty small, and a lot of people are needed to work big events. This is told to you by the interviewer when you are being hired, so you can't say you weren't warned about it from the start. It's not that bad, but that is probably one of the cons of working here.
Another con is that in the summer, you are probably going to get less work. If you are a good employee, they will keep you employed and working at other, busier venues.