My sister's 720 rode on a rollercoaster first before getting complete stability. I recommended this phone for her, being a total Microsoft fan. It had issues like random shutoffs, broken volume down button and stuff. We took it to a Nokia Care Center in Megamall, and they were able to return the device in the afternoon. However, upon examination of the device for any more defects, I realized the tactile feedback on the three soft touch keys weren't working. They took the phone again from us and we had to wait for more than 3 weeks to get it back. The device became normal again. We encountered a little problem, random shutoffs. However, with the Amber update and GDR 2, it seemed to go away.
Maybe we were really unfortunate to get a defective device, but it did not decrease my love for Microsoft and Nokia. I plan to get a Nokia Lumia or a Surface soon, if I ever get rich. Haha!