I have started a thread in the forum to track bugs that people notice on the new site. Many of the most crucial ones have already been fixed. I want to address a few of the larger ones here.
Speed: The new site was very slow when it launched but I think we are back up to roughly normal speed at this point. I have added more RAM and improved caching techniques, which seem to be making a difference. I will continue to monitor and optimize as needed.
Login problems: I fixed some problems with the login code and things should be working better now. It was automatically logging people out after 20 minutes of inactivity, which has been increased to 12. There were also problems with mismatched login states between the site, forum, and wiki. These should be resolved so please let me know if you are still experiencing this kind of problem. First though, please clear your browser cookies and logout and back in to see if that resolves the issue.
Profile images: There was an issue with uploaded profile images not showing up. This was due to some overly aggressive caching and has been resolved. However, you will not see the fix until after you clear your browser cache. If you don't know how, see this page for instructions.
Update 4/29 12:10 EST Interesting note: it looks like the search engines were crawling the new site pretty hardcore after launch, which was probably part of the problem with performance. Also, I wanted to share that all of the old attachments are now uploaded and present in the forum, all the way back to 2002.