Airtel used to have domination in terms is network but now it has lost its touch to other rising rivals like Vodafone & Idea.
It's 2G internet is very poor. You can grow your mustache back while waiting for a site to load on Airtel's data connection. Comparing it's speed to Idea, which give really very fast 2G data speed, Airtel is nowhere near it.
Now about network, it has presence in deeper parts of India but in big cities like Jaipur, Delhi, it's networks fade out in many areas and multiple complaints won't help the consumer too. They are also very expensive looking at how they are dropping their quality and raising there tariff.
Overall I'm not very happy with Airtel. I'd rather use some other network than using this.