First of all, you are supposed to do your due diligence before you book the plot. I have had a good experience with them so far. There was a bit of delay in hand off but then every builder makes use of the grace time period to some extent.
They do attend calls and respond to queries; I used to visit the site often(for my satisfaction) and this way I could be at peace that work was going on and they do respond to all queries and the hand off was as smooth as can be expected IMO.
I am a content buyer with NBR Developers. I am quite surprised to see such harsh reviews here and in case you have the proper cancellation clause in the agreement, they are bound to stick by it. Usually they require reason for cancellation and in case you can point out legal issues, they refund or there is a deduction. I would recommend that all buyers go through the agreements, discuss with the builder and their lawyers to understand what the agreement states and then get in to it! This is the approach I follow and I did have a decent experience while registering a property with them.