I had DOCOMO for 4 years and then later shifted to Vodafone postpaid by MNP. The MNP process was very tedious and took more than 10 days.
However after shifting to vodafone the charge is nominal(for postpaid corporate plan) and many things are online only. Easy to use. I am on 374 rupees plan and bill comes around 425 after taxes.
The roaming clarity was not given initially and hence I ended paying roaming when I visited home state.