I got the Xiaomi Mi5 on ebay ($299.99 = $430AUD). On first impression, it looks good. Google Play Store worked fine. The phone feels like a Samsung Galaxy S6, with some improvements, like USB-C.
Other than the phone being awesome and me getting 99% of my favorite miracles, here is what I've noticed:
The Mi phone has numerous annoying quirks, as most brands do, but everything seems to work really well as a package. I appreciate the highly regarded reputation of Mi (via episodic anecdote run-ins including a talk by Clay Shirky where he indicates that what Mi is doing to Samsung is what Samsung did to iPhone). My overall experience is very positive -- the Mi5 is a flagship. On top of that, what you get for the price is a GREAT DEAL, and I love it! I would recommend Mi to any sensible person.
23 May 2017
After too many frustrating attempts trying to get a newer version of MIUI, today met with success!
It is really quite simple when it works. I now believe that an earlier ROM was just not ready, but the current one works without fuss (miui_MI5Global_V22.214.171.124.NAAMIEB_b03a4b93ba_7.0.zip).
The outline on this page was what worked (Method 1: System Update), http://en.miui.com/a-232.html
The main benefits are: an upgrade from Android 6 to Android 7; and security updates.
BTW, Android Pay still does not work.
Before / After
It had only been 8 months since I got the Mi5, but it feels like the landscape had changed so much. Since switching away from a Google phone I've been missing out on Updates, Google Pay, Android Auto, and flagship VR.
25 Sep 2017
Updated miui from stable to dev version, hoping for frequent updates. Android Pay seems to work now. Android Auto seems to work now, with a better cable and a bit of fighting to get it to work.
23 Jan 2018
Water damage. The end.