I actually like the mobile site interface. Maybe I'm the only one, but I don't like using the full site on my iPhone or iPad.

The things I would change would be to add a couple of features to mobile that don't exist (first and foremost the ability to see the wiki on a thread, and also the ability to report posts / suggest for talk mail, etc.), and fix the bug where opening the thread to the first unread post actually takes me nearly a full page back of the first unread post (making me scroll past stuff that was posted days, weeks or even months ago).

I'd also fix the annoying bug where some threads show that there are, for example, 30 pages of posts, but the most you can get to is 29.