The MAIN reason we changed software was because the software we were own was outdated and not being developed like it should. It was gong downhill fast. This software is what most all forums will be going to if they have not.
Change is usually met with resistance, it took me a bit to get used to the difference when I first discovered Xenforo. If you're on multiple forums, you'll use IPB, VB, phpBB, woltlabBB, etc...all of these have their functional differences, and all take time to "figure out", and Xenforo is no different. Stick with it for a few weeks, what I found out is that once you get it, all of the other boards seem like they are behind the times.
One thing that really stood out to me was the Conversations structure. Remember in VB how every PM you got was an individual message? If the respondent didn't quote your reply, you had to go back to your inbox, then to Sent, look up the message, then back to your inbox, then reply, man if you had a long exchange or an old message that was brought back up, it was a total PITA. In Xenforo, Conversations are exactly like a private thread - all the exchanges are there, just like a thread. Xenforo isn't the only software that does this. Unfortunately, when you convert PM from VB there's no reliable way to make them all into a threaded format (the explanation is pretty technical, but essentially, the database structure doesn't make it very easy - next to impossible) but all new replies to old convos will thread like a post. Which means there's no need to "reply" or "quote" the previous responder's text...because they can see what they wrote just fine! Really convenient.
There are many things similar to this that are vast improvements, so try not to focus on the look and feel so much, as these types of things can be modified through styling properties. Some things cannot really be changed, at least not too easily, so there will likely be some things that really have to change (or rather, stay the way they are now)
To add to Rev's statement above, vBulletin is crashing and burning, and the vast majority of those jumping ship are going to Xenforo. Note that the developers of Xenforo were the ones that made vBulletin what it was at it's height of popularity, they left when their creativeness was squashed. vBulletin put all of it's eggs into VB5 which is a total train wreck. So you see...it's inevitable that you will see more and more boards convert away from vBulletin.
