First Windows Phone... Help?

Hello Tribe. So, I just bought a Lumia 520 yesterday but I'm completely new to the whole Microsoft ecosystem. I've been exploring the interface and browsing the windows store and still feeling a little lost, so I thought why not ask some seasoned users? I'm coming from an all-Apple background, not even installed Windows on my Macbook (would this be worth doing now?), and also have minimal Android experience.

My impression of WP8 so far has been a bit mixed. It's a good looking interface and works very smoothly on the Snapdragon S4, and it's great being able to pin anything to the home screen as a live tile, but I'm finding it hard to like IE's overly minimalist interface, and media playback feels seriously clunky coming from iOS. I don't know whether these were poor design decisions or I just need to get used to this stuff over time..

One more thig is that I'm finding the Back button strange sometimes. It feels like it's serving a dual purpose between the current running app and the rest of the OS, and a few times now it's done something I haven't expected. Is there maybe a better way for me to understand it's function?