Love tapas - to me they are great for sharing/community so take friends. Also, I think of them as appetizers for the main course - meaning you go there to hang out with friends before you head off to dinner with significant other.
I highly recommend the experience - very cool concept.
Jonathan - had one of the best birthdays at a tapas bar... great drinks, great tastings, then the chef play "happy birthday" with a violin bow and handsaw... always awesome.
Tapas bars are great for mixing loose social groups (several of friends of friends). I also find it a good way to mix multiple business contacts, like going to one with several people attending a conference. Everyone has something to talk about (the food) and the expected constant passing plates and sharing keeps everyone interacting for the entire meal.
Problem is you spend twice as much as you usually would because they entice you into trying everything and it does not take much of a nudge. We have one here in Baltimore that I love, PAZO. Martinis are $14 a piece and we never seem to leave without spending $150 for a night of atmosphere, drinks and great food.
I suppose it is worth it because we keep going but watch your wallet. It creeps up quick!