Great Tapas in Paris
Fogon (45 Quai des Grands Augustines, 6th) is good, and probably an exception as far as quality goes. It is more a modern Spanish restaurant than a Tapas bar, but that said they do do a innovative set tapas menu (or Paella). We lunched there on a Sunday and had a good experience with enjoyable food. It is wise to book.
The other Tapas I have experienced in Paris tend to be during after work drinks on Friday, when the quality of the conversation and supply of booze is more important than food. There are quite a few Spanish themed bars but to be honest the quality was average at best.
I generally find Paris has great French food but any other food is pretty average. There are always one or two exceptions like Fogon but in general if you want good Tapas go to Spain, likewise Italian, Chinese, Vietnamese, and even North African.