The Great Firewall may be the only Wonder that doesn’t require an entrance fee. It’s also one you can’t avoid on a visit to China. Basically all of the communications technology that we have been utilizing during our entire trip were crippled by the Great Firewall. Twitter, Facebook, Google, various apps, our own websites and countless others are all blocked. Loss of access to Google and Google maps on internet or phone was probably the worst of it all.
Sure, we could use Bing, but who uses Bing? And trying to use Bing Maps in Chinese to English is a crap shoot at best. Finding addresses is nigh impossible. If you really have to use all the internet conveniences that rest of the world has access to then you can use a VPN. We purchased a VPN online so that we could get around the internet blocks but even then the internet was a bit difficult.
In Civilization I basically never build the Great Firewall because I don’t really care about the technology theft prevention it provides. If someone steals my tech I just go to war with them. Harsh, I know. But even in real life I doubt the firewall provides any real benefit against technology theft, especially since you can get around it with a simple VPN.