Pros
Helps improve critical thinking, communication, organization, and customer service skills. Peak hours can get busy and can present opportunities to succeed in a moderate- to high-stress environment (including long lines, wait lists, hungry customers, etc.). Competitive hourly wage. Opportunities for advancement to better positions (e.g. host to fountain to expo to server); tips generally increase with each step up. Fun atmosphere to interact with customers, including families with children; rewarding experience and very heavy on social and interpersonal interaction. San Juan Capistrano location includes outdoor SkyRanch patio (the only Ruby's location with such a feature), which makes for a nice change of pace when you've been inside the 60s diner for awhile.
Cons
I really didn't experience many downsides at all at this job. I would say that it can be difficult to be cheerful with guests when life isn't going well or things are very busy, but that is more of a personal challenge. Also, meals for employees are discounted, but not free (unfortunately).