Hi, allow me to leave my testimonial!
Got my XPS (initially I said it was 12W12 but it was 12W10 after all) it looked OK...but then I went for a ride using GPS and Bluetooth on...only after 15min I could already see small spots on the screen (lower region) and immediately I turned off the phone and face it to the car A/C to cool it down...when I arrived home, and turned on phone on, the spots were gone but now the lower region has this yellowish white, and the top region has the white white...really pity :/
So, I went to the store and the nice lady told me that it is not a small number of mobiles that are affected but maybe all before 12W14...off course many people will not use the phone intensively to the point of 40ºC and others will think the yellowish white is normal and others will be too lazy to send it to technical support because the spot is not that big.
I'll try to hold on to this unit 'til there is a way to unlock SIMLOCK for free, being that I already spend money unlocking this one and if I exchange it I'll have to unlock it again. Really a shame :/