I had dinner there while staying in Jaipur. It may well have been because of the glowing reviews about this restaurant found both here and on other places on the net, but I was pretty disappointed with the food.
Everything else was fine - good location near the old city, good service, clean place - but the food was just so-so, and the desert was left half uneaten. Price was ok (though somewhat high for India). It seemed like 90% of the diners were foreign tourists (at least on that paraticular night), so I'm not sure how much local following they have.
All in all, you can probably do worse, particulary in Jaipur, but it doesn't make Niro's more than just a decent restaurant.