To experience 3G you need to activate a 2G plan with a special recharge of Rs.95 which will give you 2GB worth of data access. You can enjoy 3G speeds on your 2G plan with no additional costs till 10th of April by simply sending an SMS "ACT 3G" to 144/111 this is a toll free no so you wont be charged for the SMS.
The speed I'm getting at the moment is around 3Mbps to 4Mbps which is very good considering the fact that I'm not yet getting full signal strength. The upload speed is variable from 1Mbps to 2.8Mbps. The speed will only go on increasing this point forward Vodafone India will offer 3G speeds up to 21Mbps.
Note: Keep in mind Vodafone 3G is still under testing so you might not get 3G signals indoors.
We still have no official confirmation on plans, tariffs for 3G & Video Calling etc. from Vodafone yet. This will be on their official site once they launch commercially.