I noticed there's not much on this board about Cadiz so I thought I'd post a bit about what I tried this weekend.
In general, Cadiz is a great town for fresh seafood, especially if you like your fish fried. This time of year (leading up to the huge Carnival) there's a big party in the streets of the old town on sundays. Vendors sell fresh oysters, sea urchin and other shell fish in the streets. It can be pretty crowded but it's a lot of fun!
1. El Faro
Calle San Félix 15, (95-621-10-68)
Listed in Frommer's and on this board, the high expectations I had were met. Although we considered dining in the more formal restaurant, we opted for tapas which are often a better bet b/c you get to try many dishes and spend a lot less (tapas are about 2-2.50 euros each!). Favorites included garbanzo beans with shrimp, the Arroz Negro (rice with seafood and squid ink) and a roasted red pepper salad with tuna. The service was very friendly but not intrusive (one night we stood eating and drinking for 2 hours and nobody tried to push us out). Highly recommend.
2. La Vendimia
Villa de Paradas
We found this restaurant not too far from our hotel and decided to try it b/c it was full of locals. We loved the Puntillitas (tiny, tiny baby squid) served grilled with a delicious garlic sauce. We didn't like the grilled trio of skewered fish b/c it was too well done but, to be fair, I didn't say that I prefered the fish to be on the rare side.
3. Restaurants on Calle Virgen de la Palma
This is a great place to find some very casual tapas bars for lunch and dinner as well as casual restaurants for lunch. Sorry I don't remember the name of the place we tried, but if you visit Cadiz walk around here and you'll find something you like!