I have had my 1520 for a couple days now and love it... It is extremely hard to get out of the iOS ecosystem though..I keep switching back and forth between my 5s and the 1520. I can't really make up my mind.
I'll tell you another thing, once WP8 get's a real notification center and quick toggles(coming early 2014) it will have surpassed iOS IMO...The operating system is just butter. There are tons of useful features and it's not like Samsung where you will not use 3/4's of them. Really nice stuff.
The only thing i do not like about the OS is the capacitive buttons, but i can see how they are very useful compared to just a single button.
I have 30 days to decide though since i bought it full price
I am really wishing I was on AT&T right now so I could get the 1520. I might not feel that way once I get my hands on one, but the video reviews make it look so nice.