Surprised it worked as advertised
I've been attending gigs for 20 years now and have heard lots of negative things about Viagogo however I took the plunge on a recent show and everything worked as expected. I brought the ticket, got a low price much below face value (last minute the day before the show), I assume someone was just trying to get rid at that point, got the ticket transferred via Ticketmaster. Perfect!
I think the experience on this site is much to do with luck of the draw if you get a decent seller, but at least you have their money back promise to cover your costs.
I wouldn't use this site generally still due to the uncertainty and the extreme mark ups which seem to be completely unregulated by the site itself but on this one occasion it worked.
If you want to try and see if you can get a last minute deal, are aware of the risks with the site and are willing to claim your money back of things go wrong, go for it. If not stick to official resale channels via Ticketmaster etc.