The layout looks clean and crisp. Visually, I say the style itself is mediocre though. Personally I would add a little colour to the forum status icons (maybe the same yellow you used for the lastpost icon).
I feel you could have been a little more adventurous with the forum status icons which convey your sites abbreviation (GT). Something like those boxes you have further down your forum would look nice with a hint of colour (nothing to prominent) but something more exciting than the
GT text would look visually more appealing.
The threadmarkers look nice, they break out the thread display aswell as the alternative images along side them. I did notice you still have the vbulletin stock announcements icon. Maybe change that for something custom and unique for your forum?
The user online icons could do with being changed for something custom and any other image I may have missed while posting this critique.
Overall, I think you could have been a little more adventurous on certain areas of the style while still keeping it relatively simple but it does the job and that's what counts.