I'm not so keen on the colours against the gradients. Personally, I don't think they compliment one another very well. Maybe re-think the colours a little and possibly shift them around or use some lighter variations.
Alot of the images are saved out incorrectly and are showing the infamous white edging. To give them a seamless/smooth edge i would find out the background colour they are applied on and then save the images out using the appropriate matte colour.
I would rid the style of the vbulletin stock images as they look really terrible on this style, possibly check out the graphic database here and you may find images which compliment your style a little better. Also, the white matte problem is showing on alot of the vb images which gives them an awfull appearance.
Another concern is the text on the buttons look crammed and hard to read. Maybe you contracted the text spacing to much? I would give the text a more prominant/crispier look so members/guests can see the text.
Goodluck with your site.