I decided to browse some lessons on my iPhone today in my lunch hour, what a waste of time.
Firstly, following the advanced lessons link took me to the newbie lessons, as did the intermediate one so I had to browse through all the lessons, one at a time to find the one I wanted. Having found the advanced audio blog I was looking for I found I couldn't access the lesson content. I was just presented with an 'upgrade your learning' message, despite the fact that I have an active premium subscription and had logged in through the main page. I assume that I had somehow become logged out when transferred from the main site to the mobile one but there doesn't seem to be a way to log-in from the mobile site.
I appreciate that the mobile site probably doesn't get much traffic compared to the main one but please at least make sure it's functional?