I have the UX360CA and UX501VW.

The fanless Core-Y UX360CA never had any issues, works out of the box.

UX501VW has fan control issues with 16.04, which you can solve by installing a newer kernel (4.8 series) or by upgrading to 16.10. You must do this, otherwise the fan will run at loud, insane speeds and might eventually wear out. NVidia graphics will work without issues, but switchable graphics doesn't work via NVidia's control panel. I don't need the discrete GPU, so I'm exclusively using Intel drivers. Driver does crash (screen flickers) at times with my external 4k monitor. Apart from that, Powertop takes care of Power management issues. Overall, expect to spend 3-4 hours getting UX501VW set up.

I run Ubuntu 16.04.1 (no Windows partition) on an Asus X555 (8GB RAM, 120GB SSD). Works extremely smooth. I've also used the same setup on a Transformer series notebook and have had no issues at all. It's honestly been my best notebook experience - having used Acer & Lenovo before (not that those notebooks were bad)

Thanks! :)

How easy was the installation? Any crazy stunts to get it all working?

Nope. Simply installed from a USB drive. Of course, there's a little effort if you want a Windows partition, but that has been documented / blogged about ad nauseam, so shouldn't be too difficult.

Asus zenbook works without any problems with Ubuntu 16.04 for me.