After traveling in Europe, Asia and Australia, I am now in China for two weeks. Keeping in touch with friends and family and staying up to date with world news and the stock market has been doable while traveling so far, but in China I ran into a couple of problems. Of course I knew about some sites being blocked by the great firewall, but there were some additional surprises.
The Great Firewall
The Chines government blocks several news sources that have an unwelcome angle on certain topics, some porn sites and there's the disagreement with Google. See https://en.wikipedia.org/wiki/List_of_websites_blocked_in_the_People%27s_Republic_of_China for a complete list. Very inconvenient, but expected. Now what took me off guard was that my daily visit to Reddit was also blocked. A quick search on not-google didn't provide any reason why.
Collateral blockage
As a paying customer of Netflix, a site not blocked here, I expected to catch up on some tv-series in the evenings. But no, 'this service is not available in your country'. Fine, I'll play some games then, Steam is not blocked, right? 'You're logging in from a new location, please enter the verification code', sent to my... gmail account!
Clogged Lines
Of course there are plenty of other sites not technically blocked, but I found out that during certain hours of the day even those are hard to load. Complicated sites, like Tradingview, time out before any useful price updates come through and even the simplest of sites like http://www.xkcd.com take several seconds to load a picture. Meanwhile any Chinese site loads instantly, so i guess there is a line at the border checkpoint.
VPNs as solution?
The usual advice is to use a VPN to get around any blocks, but if you've read the list of blocked sites: many popular VPN sites are now blocked as well. There must be some currently functional VPN service, but I wouldn't necessarily trust them with my important accounts, like banking and trading.
So in short: Check the list of blocked sites, but realize there may be more problems than that. Get a good VPN that is currently not blocked, or be prepared for a time of relative isolation from your normal online life.