Great owners who set you up for success
Pros
Hands-on, in-person training on how to be an effective food server at formal banquets (corporate holiday parties, weddings, celebrations of life, etc.) - what's expected, what to do and not to do, how to properly mount and carry an oval tray full of entrees or dishes, which side to clear from and which side to place food from, how to set the table. I work directly for a catering company now instead of as a temp, and we mainly hire Instawork temps for huge parties: It's really a crap shoot as to whether or not they'll know what to do, or how to dress and act appropriately, because there's little-to-no training. Companies like Echo do a lot better job at preparing their employees for the industry.
Cons
No real opportunity for advancement within the company, but Echo's clients end up hiring the best temps for direct employment.