Went to Donde Carlos with a friend. Location is in an upscale neighborhood about a ten minute cab ride from downtown San Jose, the restaurant is a converted house with two stories as well as al fresco dining.
Argentinian food, on the expensive (for San Jose) side, but good quality cuts and well prepared. I don't understand a previous reviewer's comment about the portions being small... After indulging in appetizers, I couldn't finish my steak :).
The patrons were all well-heeled locals, mostly older couples or families.
Extensive wine list, mostly Argentinian and Chilean.
Great service - attentive, discreet, but not pushy. If you're looking for a quality dining experience at reasonable (100 dollars for two people) prices, a good choice.