The 820 is a much better phone than the 525. I have a 820 and my wife and daughter each have 520's. (same as 525 except for the 1meg of memory in the 525). While the 520/525 is a good phone it is not in the same league as the 820. 820 has better screen, dual band wifi, NSF, much faster processor, much better camera, front and back camera, flash, wireless charging, etc. Unless you cannot find a 820 (Amazon has them) only then would I get the 520, though I do have a 520 myself as a backup in case something happens to my 820. I usually get two days plus a few hours in battery life in my 820; but even under heavy usage I get about a day and a half. The 520/525 gets about three days of use so it does last a little longer than the 820.