The food and service in Kingfisher First is better than typical domestic First class service or even typical international business class service of US airlines. The seat is more closer to international business class seats (not the lie-flat bed kind, but ones with a lot of recline).

The price differential is quite high between Kingfisher class and Kingfisher First and not worth it for domestic trips. Jet business class is probably a better compromise.

There are a few reviews in FT Forums on IT First.