Coverage isn't an issue. But, the call quality on 2G isn't very great, expect a few call drops every now and then. This also depends on your area, some places the 2G network quality is very good, other places not so much. 3G network is very good. Haven't had any call drops yet. And 3G is present at most places. 2G network is present throughout the metro routes (both elevated and underground). But not 3G Gurgaon/Noida coverage is good. Haven't had a dead spot yet. It won't work in basements, whereas others like vodafone, airtel will.I went from vodafone to idea to mtnl. 😉All in all, best experience I've had so far, save the few call drops. If occasional call drops are a major annoyance to you, go for Vodafone. Else, I'd say mtnl.