Working fine here on WP 8.1. Tap the three bars, they dim & the whole page slides to the right (on its own) to expose a menu that includes log in. Agreed though - it took me quite a while to twig how to log on. Should be on the 'front page', especially if you're a new user?
Given up on it it won't work on my mates phone either?, we can't log in to the mobile site.
I've tried in settings for desktop but it defaults to mobile.
All was working fine the other day!
LUIGI