It may have taken an extraordinarily long time, but OnePlus is finally sending out stable Marshmallow OTAs to the OnePlus X, the company's budget phone, in the form of OxygenOS 3.1.2 (and now 3.1.3). Although OnePlus did begin offering Marshmallow in the form of the OxygenOS 3.1.0 Community Build over a month ago, it had a few bugs that needed to be weeded out. At last, 6.0.1 is ready for prime time on the X.
Here's the official changelog for OxygenOS 3.1.3:
Android 6.0.1 Marshmallow
New icon packs
Google search bar UI customization
New design of wallpaper picker
Shelf UX improvements
Long press boards to rearrange or remove
General system performance improvement
New (native Android) app permissions
New Alert Slider settings with more customization options
OnePlus Music Player
Implemented October Android security patches
General bug fixes
The OxygenOS 3.1.0 Community Build included most of these changes, but the October security patch is new to 3.1.2. 3.1.3 also brings some gesture optimizations. In addition, this stable build no longer has mobile network issues, incompatibility with some apps, and language localization has been improved.
OxygenOS 3.1.3 is rolling out over the air to OnePlus Xes that are currently on OxygenOS 2.2.3, 3.1.0, 3.1.1, and 3.1.2 right now. If you'd like to manually flash it, you can do so from here.