I've gotten lots of complaints about them. Be careful to read the fine print! They charge $100 cancellation fee even when the cruise line does not charge one.
Like other online sites whose advertisements are misleading, they advertise "every cruise on sale every day" when they sell the same cruises at the same price as everyone else.
Nothing special - just dealing in quantity.
Best to look for a reputable agent you feel comfortable with and have trust in.