I'll have to agree it's crisp and clean and the colours compliment each other very nicely. However, there are still some images which could do with being replaced like the collapse markers, lastpost markers, sortasc/sortdesc markers, and a few lingering default images.
I would also replace the default vBulletin default set mainly because it's default, most because blue and the colours of the style don't go well together.
I would also suggest with going with some custom images for some of the postbit graphics.
Overall, it's a nice clean style and I like the colour usage you've implemented but there are a few deafult images still left intact which don't compliment the style.
Goodluck with your site.
