It looks very VERY old.
My suggestion: 1. Getting rid off that awful grey background as soon as possible, and picking another color (maybe light blue), with a glittering fade out effect - similar to the one Microsoft Windows 8 tiles use. 2. Changing the confusing arrows design to the standard + and - convention, in order to collapse and expand replies and threads. 3. Space a bit (just a bit) between the different replies, so that they appear in an entire different boxes. This looks nicer and easier to read. 4. Change the titles' view of each thread - current design looks almost exactly like current Wikipedia's one, which, once again, looks anachronistic.
That's all for now, as for a 5 minutes impression.
Oz.