I do my best to help customers in distress when I am in the store(s) to help save someone from making a several hundred dollar mistake. I don't focus on the OS question instead I focus on what they actually want to do with the phone, how familiar they are with moving around smartphones. From my personal experience, WP is the easiest of all mobile OS's out there. It takes zero effort to set up, use, and make changes in settings. With iOS or Android you have to drill down into menus and that can be scary for some users.
I have use iOS, Android OS, WP7.x, Windows Mobile (SmartPhone & PocketPC in the day), Palm OS, WebOS and the only OS I haven't used was Symbian because there were no great offerings. I can switch devices and OS's without issue. I actually asked the rep at the store yesterday how to resize the icons on WP8 since I hadn't played with it yet, she at least admitted she was the least technical sales person in the store and wasn' the WP champion. Seriously, ever retail wireless sales rep should know the basics of the different OS's so they can help customers and avoid returns and charge backs.
I will say I have stopped into a local ATT store and talked with a rep who had the Nokia 920 (yellow) and he could not stop talking about how GREAT it was. At least once person there has a clue.
What WP needs is MS to pus some "real" marketing dollars behind how easy the OS is to use, how much you can do with it and help drive the sales and get developers to support it. While I have a Nexus 7 for my tablet use I am looking at the new Win8 tablets too.