Vantaggi
It is definitely a great first job to have while in high school. There are opportunities to advance to high responsibility positions early on. These positions don't pay very well, but you will have many great experiences to talk about in future job interviews. The medical is actually very affordable and the coverage is good. I left and went on COBRA, and the costs actually stayed the same, less than $100 per month. For teenagers, the benefits are pretty nice. Free movies, pre-release screenings, free and discounted concessions, and a fun work environment. They are very flexible with scheduling needs. There are many hours to be worked, and most employees are high school and college students. Management usually doesn't have a problem with scheduling requests except for holidays sometimes.
Svantaggi
If you are looking for a career, the absolute lowest level you need to achieve is General Manager. The GM at my theatre was making around $100k after 20+ years. However, my theatre was one of the busiest in the company. If you became a GM of a low volume theatre, you wouldn't make as much. The movies never close. There are no holidays, and it can be very aggravating to deal with so many guests.