I got 520 for my mum 2 months back and it is good for the price.
Adv:
Touch
Easy navigation
Quick response time
Office
Strong and hard (as usual Nokia hardware)
Nokia here map: does not require network to reach any place in the world but Google maps needs it.
Good for long run
Dis adv:
Camera with out flash
Not many apps.
Nokia gave good phone with less price!