Despite screen shots showing 8 channels, only controls single light.
The screen shots and early marketing materials implied that up to 8 of these lights may be controlled by the app. I purchased four lights with the hopes of solving a tricky mounting problem. Manually adjusting the lights in my setup now requires a step ladder and a lot of patience, rather than conveninently being able to control the lights from my phone as I had envisioned.
The app also connects to the first light it wants -- so even if you use it to control just one light in your setup, it may not be the light you expect or the same light every time.
Yongnuo's response to my support enquiry was to tell me to buy a separate remote control. (Which they do not sell and which does not exist.)
Basically this app is unfinished - the developer likely only had access to a single light, and had prototyped for the ability to control more, but never released a final version. The app icon doesn't even show the correct product.
My advice: If you need remote control capabilities, do not buy these lights. Buy a light with a working up or a real multichannel remote.
In case I sound bitter (I am, regarding this experience), I should say that I've owned other Yongnuo products before (YN600) and have been very pleased with them. I'm surprised they got so much, so wrong with this app.