Welcome to the world of vB3..
1.) Your portal isn't alligned correctly. The navbar is smaller in width to the rest of the portal.
2.) Green doesn't work for me with a Silent Hill theme.. I personally would have chosen Red for new posts, Grey for no new posts and Black for closed forums.
3.) There are still many vB3 default images used with your style.. If you want to really stand out with your design, they should be changed to something custom.
4.) Using MSN Messenger emoticons for your smilies are the biggest mistake ever.. In my experience, the majority of people absolutely hate them, and it's certainly enough to stop me registering.
5.) The bright red buttons don't match the red of your colour scheme.. I'd personally ask for them to be changed.
I previously owned a UK based Resident Evil fansite Umbrella Online, so I hope you will find this advise useful and will take it onboard. Good luck.!