I flew on Delta’s non-stop flight from JFK to Mumbai(DL 16/17) in business class a few months back. Overall, it was a pretty decent experience. Check-in at JFK was a mess, but that was because no one at Delta bothered to inform me that they have recently opened a separate terminal(Terminal 2) at JFK for business and first class passengers. So when I reached the airport, I had gone to the regular terminal and was told they could not check me in there as that was only for economy passengers! Finally, after much argument, they checked me in - absurd, huh? The lounge at JFK is really nice, very up to date. In Mumbai, they have to share the lounge with about 10 other airlines, but that’s understandable in view of the work going on at Mumbai airport.
The flight was good, although the seats were disappointing - Delta still has the old-style cradle seats in business class which is ridiculous in this day and age. They are pretty wide though and recline to 160 degrees so you can get some sleep. The flight attendants were nice, it was primarily an American crew based out of Atlanta so you got that Southern charm. It was strange to only have one Indian crew member in the cabin, though, maybe they had more in economy. Food was surprisingly excellent - there were four choices(Western veg and non-veg and Indian veg and non-veg) for every meal served which is a lot. I mostly tried the Indian food which was really good, and the crew were nice. I requested yogurt with every meal since I’m under doctor’s orders to eat a lot of it, and they made a special effort to ensure I always had yogurt, whether it was supposed to be served with that particular meal or not. They have a nice IFE system, with personal 10-inch LCD screens and a good selection of movies. The flight to Mumbai was punctual, coming back we were delayed by an hour which was due to congestion at Mumbai airport - seems to be a recurring theme these days. Baggage handling was good.
Overall, a good experience; however, the seats do need to be updated to full flat beds. I was chatting with the lone Indian crew member and he told me that Delta is getting new Boeing 777-LR planes in Feb 08 with full flat beds in business class. In view of the popularity of the Mumbai flight, he was hopeful that the new planes would be allocated to this sector. If that happens, I would say it would be the best option for flying to Mumbai.