Its battery life is crazy and performance in extreme budgets were much more crazy because windows phones were much optimised (lumia 620, has 512mb ram and I play a lot of games without lag !!! But if we take and Android from that year, it's not even usable today without custom roms or root)
but sadly it didn't have many apps in store (like Google, YouTube, Maps) and the main reason Which made me switch is Google maps/Android Auto and end of support
"Windows" phones were optimised and better than android and iphone at those times...