At the bottom of the Mobile page, there is a nice big button "Go to the full site". That is great.
However, it took me some time to get back to the mobile site again on my mobile phone. I was stuck with the full site forum. I finally found that by clicking on the very tiny word "mobile" at the very bottom of the page, you could get back to the mobile web pages. I do not know any other way.
Perhaps a big button "Go to mobile site" on the full site page could be added to make it more obvious?
I was going to complain that the "Unread Posts" was going to the first page of the thread instead of the last when you click on the thread name, but then I realized that when you click on the arrow after the thread name, you go to the recent post. So I am happy with that.
Overall, it looks very good.