Got my iPhone 5 yesterday.
32GB Black. Three network.
PAC code all sorted (old number moved), synced to iTunes/backed up etc.
3G data is blisteringly fast now (O2 was dog slow) and great 3G reception/speed in all sorts of places where it struggled before on O2. (Well done Three.)
Data is unlimited now.
AirPlay performance as good as ever. (Never had any problems there anyway.)
Display quality is fantastic.
Now paying £5 less per month than old (O2) contract and £4 less than equivalent new O2 contract. (Although O2 could only offer 1GB data.)
Much of my happiness is down to better contract/better 3G reception/faster 3G speed/unlimited data etc. but the iPhone 5 is certainly the icing on the cake.
I know i'm going to get a 'beating' for liking my new iPhone but I don't care
Note: This should in no way be interpreted as criticism of any other type, or brand, of phone as I have never tried them.