I use an inadequate laptop displaying on a nice big external lcd panel, a thoroughly obsolete version of Windows with an ancient version of Firefox (it'll still support html5 if anybody actually used it properly), and my only issues are with modern bloatcode shiny sites or those mucked up to chase the shiny new browsers. I am interested in the content, not the latest ephemeral bells'n'whistles, accordingly I ignore the shinies. Style is not a substitute for content. The simple text-centric nature of pfm suits me and my system perfectly. As for 'phones, I have no idea nor do I intend to find out.
I echo Tony above, I cannot recall issues caused by pfm.