Overall I think it is cool that you implented everything without shutting the website down
But I dislike the new design. I think it is much more confusing then before. Now it looks like the 0815-Forum on the internet for ~15 members.
But I think that a different coloration would help it! For instance should the "middle part" be in a different color then the outside part, also the button coloration is a bit distracting.
Maybe don't use blue as a highlight... Also the top ad banners are covering the actual global-flat cover and this just plays its part in the "confusing" thing, because it seems much more unorganzied.
Also from what I can see while I am posting, is that the "Home - Help - Search - Profile etc etc" buttons don't have a background, so it's not clear that they are even buttons. Thats another thing about the coloration
But what I really like is the function, that you can see new replies and unread posts since last visit. Also the placing of the new forum topics on the frontpage is great.
Oh, and these things that come sliding down when you hover over the mainbuttons (I dont know the name for it) is nice!