I've only had the plugin installed for like 10 days (paid version) and already have doubled the amount of normal visitors. And it keeps increasing by the day.
Some of my top landing pages are now more popular & more visited in other languages...than in my default English language.
It took about 2 to 3 days for the hits from other countries to start appearing slowly. But the last couple days they've been increasing dramatically.
I have vbSEO installed as well, and also recommend that for others. As its important to have the title keywords in your URL as well & ending with .html. I haven't tried the vBulletin 4.0 URL optimization method, so i'm not sure how well that one works.
One thing I know for sure is , you will see very little keyword traffic increases if your pages are not SEO optimized and still end in .php
Also, I never modified my vbSEO Sitemap to include the other languages. Infact I disabled vbSEO Sitemap completely so that Google could slowly discover everything on its own. As it has done correctly. You don't need to submit your site to different google versions either ...It will find your content automatically & place it in their appropriate search engine. (Google China, Google India, etc)
The hits were increasing so much the last couple days that I had to disable "who is online" and other cosmetic features of vBulletin to keep server load down.
Michal is a genius and this plugin kicks ass.
The only bug I ran into when installing was that I have a 'branded free' version of vBulletin. So when I removed the copyright notice, it messed with the functionality of vBet as well. But all is well now & the staff here helped me resolve.
PM for url.