Due to circumstances out of my control, I had dinner at Cascal in downtown Mountain View twice within four days. I'd been there once before, a while ago for lunch, and generally enjoyed it then except for the overly-sweet white sangria.
Both visits this week were a bit disappointing, though the Sunday evening visit was worse. The restaurant was quite crowded both times. Both visits I had the tapas sampler plate, pitchers of red sangria, and the zarzuela. The tapas sampler is good, though difficult to share with more than 4 people. The red sangria was overly sweet but still good the first time, but very watery the second time. The zarzuela was so-so both times.
The ceviche sampler was okay -- the scallop ceviche was the best. The paella was very disappointing, a tasteless, dry concoction (but I did go to Spain last year and so may be pickier than most). The asado was dry, and the Mexican shrimp, sopes, roasted eggplant, and chicken kebabs were just so-so, but I did like the side order of Spanish fries.
Overall, I think the restaurant is stylish, noise level is a bit loud, the service has kinks, and the food is not very authentic and a bit disappointing. That said, it's fine as a fun and somewhat more upscale place to meet up with friends in the area.