Cafe 21 is a restaurant that somehow manages to succeed in being almost all things to all people--and serves up excellent food in the process. I was in San Diego for a conference and ended up having dinner here twice in three nights, with different groups of people.
My experiences were on a Monday and Wednesday night. The service was attentive, friendly, and the staff all seemed to work together at getting food out to the customers in the restaurant. It was not busy when I was there (6-8pm both nights) so my guidance on Cafe 21's service on busy weekend evenings would be speculative at best.
As others have stated, the menu is eclectic and varied. The restaurant claims it is nominally Azerbaijani--if this means that they serve up fantastic specials in Azerbaijan like 1/2 a rabbit on black-eyed peas with a sweet pepper glaze, or one of the best mahi-mahi entrees I've ever seen (and tasted), then I'll eat Cafe 21's Azerbaijani food at any opportunity.
They have some really nice menu items you don't often see--the tapas/small plates menu has a standard happy hour before 6pm (plates are in the $5-8 range); they have six kinds of sangria; and their wine menu covers all the bases. They also claim to be famous for their avocado and portabello mushroom fries. I've tried both, and they are excellent. The avocado fries are a bit rich and decadent, while the portabellos are just about perfect--not greasy or heavy at all.
Cafe 21 also has outdoor and indoor seating; a very nice, relaxed atmosphere; and best of all, the high quality food will not break your wallet. Both evenings, a meal for two people, including an appetizer and several drinks (once including dessert), were right around $100. If you keep the drinks to a minimum you could easily slip out with a bill of $25-30 per person, pre-tip.
One last warning (and it is a good one): the Pear Salad is absolutely the largest single-peson salad i have ever seen in my life. Our server told us that it was OK for one person and "could be shared"--unless you are going to make an entree out of it, one person will be hard-pressed to eat the entire salad. Two or even three people could easily share it and be satisfied. And, yes, like most everything on the menu, that salad was delicious.