I own a oneplus x in white at the moment. The only issues are that for me on OxygenOS video playback stutters and is just generally bad, and also its still on 5.1.1 which sucks, as I would love to get 6. (Haven't used a custom rom because oxygen has a great amoled theme) Also patchy LTE from what I have heard (lack of bands), but I'm not fussed as my phone plan doesn't support LTE and I really don't need it.

Apart from that, the build quality is sublime, the screen has really good colour, and in general its pretty well rounded. The omission of features like NFC is a bit annoying but I can live without (I do miss mobile payments though) The build and design are the main reasons I bought it, its top stuff.