I have travelled many times with Indigo and here is what my experience is;
Bookings: these days many online ticket booking portals are available so thia is no more a big concern about Indigo.
Check-In: Most of the times during my check in I have noticed that more than 50% checking counters are not working and the queue for all flights is on the only active 1-2 counters ( This happenes at both Delhi & Mumbai Airport) .
Boarding: The boarding generally is delayed ( although in India it is a trend) but the irritating thing is that they don’t even display that the flight is delayed ( if delay is less than 1 hour) untill its only half hour left for take off.
Seating & Comfort : Its almost same in all the flights but I want to mention a unique thing that I noticed in Indigo seats. The food tray and the seats were tied with a wire instead of proper screw ( imahe attached) and nowhere I can see a place where I can give my feesback or complain about this.
It was horrible to see such carelesness.