Been using this one since Jan 2017 in india. It still works good enough considering that I paid only about RM400 used ( RM1k+ new) . Battery life is starting to deteriorate as of current, heating is some minor issues. 3GB ram is still usable enough in 2018, and internal 25GB usable is enough that I don't always have to clean up ( mayhaps once/twice per month) . Oppo doesn't seem to like supporting their ColorOS as of recent update, honestly, so I'm stuck with Android 5.x. Only recently found out that it has fingerprint scanner and it works pretty well. Currently using Microsoft's Launcher and a custom icon pack to give it a fresh look and performance doesn't degrade much or at all, I've always disliked that ColorOS default UI ( bloody iPhone UI grhh! ). Fingerprint can be used to encrypt apps by apps basis, handy to hide your personal thingies conveniently ; ) without having to remember passcode/pattern.
However the ram management is really brutal. Occasionally it'll terminate Microsoft Launcher and use the default Home screen instead, but albeit only once every 2-3 weeks. However, don't hope for custom status bar, notification bars, or even some handy background apps. ColorOS will just terminate them even when you specifically told it not to. Even tried tinkering with securities, permissions, etc, but nada, it'll just boot it after a while.
Honestly not bad if you just want it to work in 2018. Has 3.5mm jack, microUSB, microSD slot, dual SIM, acceptable speaker, no henious notch, front-facing fingerprint scanner, battery life should expect about a bit past half a day after 2 years of use.