Well it prevents 99% of the people who don't know how or don't bother setting up VPN from accessing prohibited content, that's the intended effect. So I would say it's working well.
And that's just people who explicitly use it. With that kind of market penetration basically everyone knows what to do, or who to ask if they want to access some geoblocked service in the future.
According to my observations now here in China, your stats are wrong.
Edit: Just to substantiate, many people I spoke to vaguely know what they would see if they get unfiltered internet, so there's not really much motivation to bypass GFW.
Sorry, but this is an anecdote. Do you have a source that shows some usage? I'd love to see that, whichever side it agrees with, but personal experiences rarely generalises to nations.
Interestingly with censorship being such a sensitive topic in China, it's hard to find statistics on VPN usage rate. I will just say that I'm a Chinese citizen who visits China regularly every year. My impressions can't be too far off from the actual stats.
On the other hand, it blocks 0% of people who have the intent to access that content so it doesn't really work at all for the people it's supposed to stop.
Edit: another one is pretty close as well: http://insight.globalwebindex.net/chart-of-the-day-90-millio...
And that's just people who explicitly use it. With that kind of market penetration basically everyone knows what to do, or who to ask if they want to access some geoblocked service in the future.