When we have our smartphones on we are usually constantly using up our data, but the new Windows Phone 7s are like little data sucking vampires. For many users they are finding that their phones are using an abnormally large amount of data from their plans. For some of the people they are experiencing a loss of data up to 2mb per day, which eventually adds up to 1.5GB of data. For people who have the 2GB data plan this is a really big blow for them since 3/4 of what they pay for is going straight to things we are not even doing. There is another issue that makes this even worse though. The Windows Phone 7 does not connect to wi-fi when it is available, rather it chooses to stick with 3G and this is causing a large drain in data. Hopefully Microsoft will be able to fully fix this in their newest patch which is coming out soon.

Sources: Engadget WinSupersite Microsoft Answers (1) Microsoft Answers (2) HowardForums