Is Instagram now a killer-argument for not buying a phone ? :P
But to stay on topic: I tried WP7/8 a few times, and it is really smooth, but for me the Interface was a bit jumbled at times. I don't really like it when my icons are just floating in "mid-air" basically. There's just too much "empty" going on in the interface.
Not that I want my interface all cluttered up like some OEM's think it needs to be.
Phone: LG Nexus 4 16GB, running Android 4.4 KitKat KRT16S
Tablet: Asus Nexus 7 32Gb WiFi, running Android 4.4 KitKat KRT16S