Like the Moto 360, the OneWatch boasts a circular OLED display - protected by sapphire glass, no less, and the watch face is protected by titanium borders. The watch has a crown to be configured, and most interestingly, it is said that its leather strap is home to a curved battery which can be wirelessly charged.
The OneWatch appears to be comparatively smaller than the Moto 360 and other Android Wear gadgets, which is good news for those preferring more discrete watches. Mind you, so far nothing suggests the OneWatch is another Android Wear device. Chances are equal that OnePlus will opt either for Google's watch-centric Android build, or for a home-cooked Android ROM. Perhaps the company can also get the Cyanogen team on board. We'll see.
At this point, the launch date and other details are amiss, but if the OneWatch is in advanced-enough stages, we ought to hear more about it pretty soon.