I've been a vBulletin admin since it was first released and was an admin on multiple sites running UBB before that. There are some cool features included with vBulletin that most people don't even know about, although the admins on some sites choose not to activate all the features for various reasons.
For instance, look near the top of the thread. You'll see a gray bar with some links that say "Thread Tools, Search Thread, Rate this Thread, Display." There are some interesting features in there that can be customized to help tailor your browsing experience in a way that's better for the way you use a forum. You can subscribe to threads and then read those threads from within your user profile page.
One of the most overlooked tools is the "Display" function. Click on that and you will see some links that say something like Linear, Hybrid, Threaded. These are alternative views that change the way the forum displays threads. If you're used to reading forums with a "threaded" layout, then you'll want to check that out as it can be useful.
Two of the more important core features of vBulletin, the Groups function and the user blogs function, have been disabled by the admins here on the PRS forum. That's just the way they chose to set it up. But the user blogs is something I wish they would activate because it's great fun. That allows each user to have their own private blog which is integrated right into the forum suite. That can be really cool for sharing "project-type" information with lots of photos (say a guitar restoration of an old PRS guitar) or posting musings and thoughts that might not really fit neatly into the main forum structure. vBulletin has a built-in feature which then dsiplays all the latest and greatest blog posts from the members along the side of the forum in a sidebar. That way you can see what members are posting in their personal "PRS" blog. The blogs can be activated very easily with a few settings in the control panel, and I hope the admins will consider doing that (if you need any help I would be more than happy to assist).
I love working with vBulletin. But most people -- even most admins -- don't know it's true potential. It's much more than a forum, it's an integrated suite of tools designed to help build a vibrant, interactive community.