I have been travelling frequently on the Jet Airways Delhi-Brussels flight this current year. I found overall Jet Airways a good Airline compared to many an International Airlines.
The food is palatable particularly for Indians, the cabin crew is warn and friendly, I found the male cabin crew much better, the check in is OK and the flights are generally punctual. However I would advice you not to buy anything from the on board flight shop unless you are familiar with the brand and quality.
I do find that their web-site is not very user friendly for frequent fliers. I have had a lot of problems trying to get my points and am still not satisfied.
I travel frequently to West Africa and used to travel by Ethiopian Airlines, the fare being cheaper. The less said about etiopian Airlines the better. I found that travelling by Jet Airways by paying a litlle more was any day value for money and worth every penny.
Though I do have a complaint that they are very strict about baggage allowance and even after being a frequent flier did not give any extra allowance and charged me for excess baggage. They need to be more sensitive to their frequent fliers.