Surely one of my favorite features of the Samsung Galaxy Nexus is the ability to show your data usage over a monthly cycle. In the data usage area, accessed via Settings | Data Usage, you can set a mobile data limit and track your data usage by application. While the Data usage feature is not an exact measurement, it does give you a good idea how close you are to your data cap. This is a feature of the Ice Cream Sandwich version of Android (4.0), and will be available regardless of your carrier once you upgrade.
The benefit of being able to set a data usage warning at a user defined level and a data limit at another level is fantastic. Once you hit the data limit, the mobile data network is disabled to help you avoid overage charges. Thus if you have a 2GB data plan, you can elect to be warned at 1.5 GB but set the limit at 1.9 GB. The reason I would set your data limit, the point where mobile data is disabled, below the actual carrier cap, is to account for the inaccuracy that the phone and carrier bring. It might be wise to do several checks online to verify how close this measurement is. It also goes without saying that if you hit your data limit and still need to continue and are willing to take the over-data charge, you can quickly adjust to allow a higher data limit.
This utility gives you a great deal of flexibility. In addition to showing how much data usage a given app has used, it also highlights the number in MB for both foreground and background data usage. For apps that are huge data hogs, you can restrict the background data usage on a per app basis as needed. I was shocked to find that my Evernote app was using approx. 1.4 GB of data per month. It led me to reduce the number of folders that I replicate to the phone, for offline use.
In addition to setting a data limit you also have the option to define the usage cycle. Thus if your billing cycle the Starts on the 12th of each month you can make this adjustment.
In full disclosure, using this utility is the first time I have seen this phone become unstable. I experienced a spontaneous reboot, unresponsive soft keys, unresponsive power button, and overall system lockup for 2-3 minutes. I only experienced this issue when I was adjust settings or drilling down on details for a specific application and the phone seemed slow to put the pie chart up for the app in question. Others I have talked to have not seen this, so I am not sure what was going on or what would cause such an instability.
Overall this is a welcome feature and it puts the power and control of data usage back in the users hand.
