Have just installed it, love the font and display improvements - it all looks a lot clearer but the major downside is that it is ridiculously slow on my iPhone 6+ compared to iOS 10.
Perhaps it’s doing some housekeeping in the background since it’s just been installed but if it continues to suffer these speed issues I will be recommending to friends, family and colleagues that they do not upgrade as it is substantially slower and this does not outweigh the benefits to me.