After spending some more time looking through this forum i'd say my main gripe now is the so called Ajax loading. It is soo bad, and slow, from a users point of view. If you try to browse this forum like I do on many other forums it "sucks" (strong word...but I could not find any other). Take just such a simple thing as you are in the main forum, a bit down on the page, and you go into a subforum. When you go back you are, after the Ajax loading has finally finished, back in the main forum...but at the very top of the page?!?! So now you lost where you were and have to find your way back to continue where you were.
Take any other public forum, perform the same task, and you will notice that:
You will be taken back immediately to where you were on the main forum page.
You are back on the main forum page on the same position that you were before.
It all works nicely since this is what web browsers are good at.
Ajax may be good for many things but when used improperly, or in a bad way, it offers no advantage over native web browsing.
Again, this new forum offers some nice and good improvements to many other forums. But it came at the expense of loosing basic, expected, user experience. If you could combine both worlds then you would have a really good forum that probably could fit both new and old users.