This is a really lovely design - and anyone who knows my feedback knows I have strict standards so I don't say something like that often.
Nice logo area - crisp and intriguing.
Like the use of different green for the login slider. It separates it off as a different, important function. I love the colours and the way you have moved components around so it doesn't look like a standard forum at all.
How do you do that gorgeous announcement block top centre?
It's really striking. However I spent some time wondering why my hover on the titles had no effect. Can the preview content be accessed by hover? Seems more intuitive.
Also some of the preview content is not solidly informative. It goes for friendly, but in an expanded way more appropriate to the main text after opening that section fully. I can help you with that if you like, an example to show what I mean (tired right now)
I think I would move Statistics down the left sidebar. It's not the first thing a visitor wants. Also while your stats are low you don't want to feature them so high.
Absolutely love your Category bar design - very original, and the forum icons.
Why does that bloke keep bobbibg up and down in the Twitter block? and why the big space between the content and his bobbing space?
Having got the designs and structure going I'd put an example post in each of those empty forums with appropriate content. Empty doesn't look good.
Thanks for the comments - very helpful and very much appreciated feedback. I've moved the Statistics down as you mentioned and we're working on content for all the forums without posts over the next couple of days. Absolutely would love any suggestions you have on that preview content, so thanks for the offer.
As for the announcement block, I found that you can swap out the gradient image for an actual one then just have it aligned with no repeat.