I have been a vodafone customer from the last 7 years when it was known as Orange and later Hutch. So I have been part of Orange, Hutch and now Vodafone. Primarily I have purchased this sim card based on its reputation and I have not been disappointed.
The most important thing that you want when you purchase a sim card is the network coverage and vodafone has excellent network coverage. I am from Mumbai and have been to Delhi, Hyderabad, Tirupati, Madras, Bangalore, Nasik and I never had any problem with vodafone and its network coverage. The customer service is also good and quite helpful.
The one thing that is worrying about vodafone is its cost. It is a bit costly and you have to recharge with some special monthly packages to avail benefits of SMS and call rates.The internet service of vodafone is also quite good.
All and all a good a service provider, though a bit costly, but you won’t definitely say that my money is wasted.