I just updated FF Nightly on Android and the new Photon UI is very big, very white and very obtrusive feeling in comparison to before I updated. I've got a pretty small android phone, I'm sure it looks better on the phablets of the world, but I ask for a dark UI option and small screen footprint please.
Edit: Found some images http://www.androidpolice.com/2017/08/08/mozillas-new-photon-... I just noticed, it recolors my system stsusbar too. So, it's white on white while FF is open. Everywhere else it's black.