Pros
You learn how to shoot weddings, with little to no experience.
They provide the equipment for you to use, so you don't have to buy the things yourself.
They critique your photos, so you know how to improve.
Cons
Pay is abysmal
They don't allow you to grow. They won't call you for another wedding for months but won't actually fire you and without any reason.
You can't keep the photos you take for your own portfolio.
They want to train you to take photos of you haven't shot with them in two weeks.
You aren't compensated for gas.