This is the understatement of the year!
I think we can well conclude vBulletin 4.0 was at best a beta, and maybe even an alpha test version released under the false "disguise" of an official version...
On the good side, it means you don't have to take all the blame for the problems that popped up , and your dedication to the site is in my opinion, despite possible delays, without doubt .
I know from personal experience how hard it is to get these things right... and how it may seem nothing happens, while hard work is being done in the background.
Keep up the good work, and lets all hope vBulletin will make it really right in the next couple of v4.x releases.