hi!!im gonna get a nokia lumia 520 for my sister...i juz wants to know whether does the nokia lumia 520 got any common problem something like lags(i know windows phone doesnt lag on low end devices oso)but still i juz wants to make sure...btw,is there any differences between L920 vs L520 in terms of functionality.....i saw the L520 specs...its internal storage is 8gb......im juz scared whether the 'other' storage problem will be a serious prob to this phone....Thnx