Got mine yesterday (Sweden).
I love, love, love this device. It's smart, sleek, and powerful as hell. I've had zero issues; the back casing was a bit tricky for me to pry off, and the phone restarted once for no apparent reason. But everything seems great otherwise. Acceptable warmth build-up while it's charging, battery is doing fine and improving, and Hello has a 95% success rate.
I owned a HTC 8X previously, but got a bit disillusioned after a while with the (in my view) rather messy design language of Windows Phone 8/8.1. Switched to Android for a HTC One M8, but finally got pulled back in by Microsoft with Windows 10 and the new devices.
So far incredibly impressed by Windows 10 Mobile. It's so gosh darn clean and elegant compared to Android. No wasted space; better looking UI; and everything just makes more sense.
Thoroughly recommended phone!
Edit:
For good measure, I'll mention my one complaint. After owning the HTC One M8 for a year and a half, the speakers on the Lumia 950 XL feel rather weak. I'm used to listening to podcasts without earphones while doing the dishes and so on, and the M8 was a lot better in that one regard.