I only have 190 mb, and have had the phone for close to 3 weeks. I do use wifi more than 3g or edge.
I've heard that while it says 'unlimited' data, that ATT has a cap of 5gb a month. Doesn't look like anyone here is coming that close to that. I hope someone does though, because I would like to see them sue ATT for false advertising, if you say 'unlimited' I don't see how there can be a cap.