I upgraded to a 635...kept my unlocked 520 and cleaned it up...made it an OFF LINE warrior (Here Maps/drive, Offline Wiki, Offline Bing Translator, offline Encyclopedia
Offline GPS apps, Offline Nokia MIX , Offline Next Gen Reader...you get the idea.)
so loaded up the 16GB SD card.
Keep it in my car for emergencies and update/charge it once a week.
Also good to use as a walkie/talkie text device when needed as long as there is wifi