I've tried it with a Lumia 925 and WP 8.1. Was connected via Bluetooth and directly in several apps (also Runtastic) recognized.
Thanks to the built-in NFC day I can start my Laufapp even easier.
Just an app like "NFC LaunchIt" download and so describe the built-in NFC tag. Then open this app, if you hold the phone in the vicinity of the chest strap.
Could not be simpler. No more searching for the app.
The haptics correspond to the level of function. All the great satisfaction.
What can I say?
It just works perfectly, even with Windows Phone.