I must have one of the first of these devices in the UK. I'm an IT guy and produce gaming software in my spare time. I wanted a stylish light weight laptop I could take with me on holiday etc. I quite liked the surface book but the price was way too high for what you got, I liked the XPS 15 - great specs but to get an SSD meant a jump in price, oddly I didn't like the XPS 13 in the flesh, the UX550 looked a bit too big and ugly. Luckily this came out just before I went on holiday and HP said they could deliver it before I left.
First off, if you want to play modern games then I'd recommend the i7 version - I tried Borderlands 2 Prequel and it looked great and seemed to be keeping up but would lose the keyboard input while playing - I guess my i5 model didn't have enough horsepower. Lighter games it would be fine. For my development work it's great.
I was using the laptop in 42 deg heat (C) and it didn't get overly warm. Weirdly I haven't hear a fan come on yet - does it have one? Keyboard is fine. Screen is nice but only uses the full width available at certain resolutions - not sure why. Sound is fine. It just feels like a nice laptop. I still prefer the look of my friend's surface book but he spent £1700 on his and I spent £990 on mine and I suspect mine is more powerful. The keyboard lights up but I find it a little too bright with a fair amount of seepage around the keys - there might be a way to turn it down. Battery life seems to run forever - I suspect over 10 hours in normal use but I didn't time it. I've had to bugs or glitches - it did ask me to reboot a few times over my holiday to get updates but has been rock solid.
Overall very happy with it. For the price it's very good. I'd still prefer the i7 model though.
Mike