I have just tried it with my mobile and i found it very hard to navigate as everything was to big so it would take a while to get to the bottom of the forum. I will test out the mobile phone on another forum and see if it is any better.
EDIT: Tried it on my mobile on a forum that uses it. I think that it is a lot easier to view forums also if you do decide to get this Daivd then you should consider this as well http://www.vbulletin.org/forum/showthread.php?t=173239
because it auto detects mobiles and assigns them the mobil theme.
It is not a long job of installing this it takes max about 2-5 mins.
I have installed this at my forum for test use if you want to try it.