I had an ATT Lumia 920 which I bought at Microsoft Store online (I live in Canada and my carrier is Telus). Had to wait till May 9th but got my phone unlocked and was using it. I was disappointed with camera quality (images were blurrier than what I see in the view finder when taking the photo) and the phone was intermittently losing the network for a minute or two. Also it started feeling too bulky and heavy. After 925 came out I got really excited about it, went into the MS retail store and told them about the problems with my 920. Although I didn't purchase Microsoft Assure at the time I bought it, they still made and exception and accepted the phone for replacement, because I didn't have any business with ATT to be able to process return through them, and service through Nokia would require me to ship the phone and wait for quite a while. They also agreed to give me 925 instead of 920 as a replacement charging me the price difference. I was surprised that Microsoft Store price for 925 is currently $699, and TMo's price for a phone without subscribing to anything is $579. Next day I went into the MS store and they were more than happy to price-match TMo's price and refunded me extra $120+tax that I paid.
Same day I called TMo and submitted an unlock request (I do have a long-standing prepaid account with them, which I use with a $2/day plan only when I go down to US, so my ARPU is roughly $8-10/mo). Next day I called again and turned out my first request wasn't filled in properly by the rep, so the rep had to re-create the request and said I should receive an e-mail from them within 24 hours. Still waiting.
After I get the phone unlocked it should work with all carriers in Canada (the big-3 and Wind/Mobilicity), since it supports both AWS and regular HSPDA/HSPDA+ and LTE, which I find amazing. I'm also going to try flashing EURO DEV firmware in case internet sharing will not work right away on Telus.