A formerly great software rode into the ground by lousy management.
Was a long time user of this software. Version 3.x was the premiere software at the time it was released. Since then, with new owners, new developers, and (just as important), serial departures of staff- developers, customer service reps, project managers, and marketing folks, this software needs a post-mortem. Not only does the current software version (5.x) not work in a production environment, but they never fulfilled their promises about what would be delivered in 4.x (after promising many features, when new staff came on board, they disavowed ever making the promises).
In short, the current state of vBulletin is a mockery of what it once was. If the phrase "Buyer Beware" ever had a more applicable meaning than for those who might buy this software, I can't imagine what it might be.
If you buy this software, understand that they will not guarantee that it will work, and if you want a refund, they will deny it as they have a policy that once you download it, you bought it (though, this seems to fly in the face of consumer protection laws...some have reported success with disputing charges with their credit card issuer).
If I could give a lower rating than one star, I would. If you have the misfortune of buying this software, I feel bad for you.