I've had tapas all over including from Spain and I love my tapas.
Serrano does a very nice job with service, decor, and ambience. No qualms there.
Their menu is average. They have your typicals like cheese plate, meat plate, patatas bravas, and Spanish tortilla and paellas. There are a few interesting tapas. But nothing that truly jumps at you. However, the tapas we tried were very tasty. I thought the Spanish tortilla was one of the best I've had even compared to Spain. The paellas were also one of the best I have had. We tried there mixed paella and the angel hair one. Both were excellent.
The price is the main problem. It is completely over priced. It is literally double the price you'd pay normally in the USA and quadruple what you pay in Spain. Although the food is tasty, it's not THAT tasty to make it worth it.
The alcohol menu is extensive but also completely overpriced. For instance, a bottle of bud light costs $6.50. We did order the sangria for $44 and it was a very good sangria. I'm just not quite sure it's worth it though. Maybe every once in a while?