I received my kit today, but have only had a few minutes to "test drive" it. Set up was extremely simple, just make sure you have the latest software update on your nano. I slipped the transmitter under my shoe laces (see below). When you plug the little dongle into your iPod, you get a "Nike+iPod" menu item on the main screen. From there you can choose what type of workout you want (time, distance, calories, etc.). Once you choose that, you can choose a playlist. Then the voice tells you to walk around a bit to activate the transmitter. After a few seconds, the voice tells you to begin your workout and the first song fades in. You can press the center button on the nano to get your time and distance at any time during the workout (the music fades and the voice speaks) and every 5 minutes the voice announces how much time has elapsed. I haven't played around enough to see how customizable all of these setting are.
Since I'm a bit busy today, I ran on my treadmill for 10 minutes instead of going out for a proper run. The time updates were nice, and the distance was two-tenths of a mile off of what my treadmill said at the end of the run. I don't think we can read much into it, because I have no idea how accurate my treadmill reading is. I'm sure there will be many people who will test the distance accuracy in the next few days.
As for using it with non-Nike shoes: The transmitter tucked nicely under the laces of my Saucony Hurricanes and didn't fall out during my 10 minute run. Before I take it outside, though, I'm going to sew a piece of velcro to the tongue of my shoe and stick the other piece on the bottom of the transmitter. Between the laces and the velcro, I think it will be pretty secure. I couldn't feel the transmitter against my foot while I was running. It would be easy to forget it's there. FYI - I wear a size 13. If your feet are significantly smaller, or you use a different shoe, I can't really speculate if the transmitter will fit under your laces or not. [EDIT: I just remembered that I'm married and my wife's feet are much smaller than mine. The transmitter fits perfectly under the laces of her size 6 Mizunos.]
I'm also not sure if the orientation of the transponder affects its accuracy. I'll have to do more testing over the next couple of days.
Another FYI - I won't be online much for the rest of the day, so don't get annoyed if I don't respond to your questions.