Xbox Arrives on iOS: Earn Achievements on iPhone

[MoHasanie]

Wow this sounds awesome, but I thought this was supposed to be an advantage of purchasing the Windows phone, or am I mistaken?? I read somewhere that Microsoft will do this for their Windows phone hoping to attract Xbox Live users but then why release it on iOS?
hmmm, now I'm really confused about getting the Nokia Lumia 920 or the Iphone 5...