Unless you have an unlimited data plan, many mobile users are always struggling with keeping within data limits. Exceeding these limits can often times result in a massive bill. 4G, HD video, Retina optimized online content all proponents of the problem.
For iOS users especially, there is not a toggle or control that you can configure to switch data off when you have reached your data limit. Account managers usually getting text/email notifications once 70% data has been used but this might not help other users if sharing a plan. On the other hand, Android handsets as old as Galaxy S3 allow their users to set data cycles depending on their billing dates and enables them to keep their data usage in check by enforcing usage limits.
Once workaround was to call #3282 or #DATA to receive usage information via a text message but it was inconvenient not to mention forgetting to check constantly
However, In a recent update of “My Verizon Mobile” app, Verizon users can now monitor their data usage through the iOS Widget. I believe this is was a much needed feature and will benefit a lot of users