A lot more comfortable in the past few years. For example the things you see in stories about China- line cutting, spitting and pooping in the street. These are nearly unheard of now (in Shenzhen, rest of China it still happens). Up until three years ago if you wanted service in a restaurant you would bellow fúwùyuán in their general direction, they would stare at you blankly, have a shoving contest with their co-workers to see who had to deal with the foreigner and eventually someone would come over. Now a discreet US style hand gesture usually is all that is needed.
As a very loose comparison with Hong Kong I would stay there is less English in Shenzhen, but in terms of modernity and cleanliness it is now equal. I actually find Shenzhen locals to be more polite in recent years, although it is far easier to find foreign goods in Hong Kong. You can get basically anything on Taobao now though it’s not a huge problem. Shenzhen changes fast- so this is all a recent development.
>Do you see a late 20-something white software engineer as being capable of making a living in Shenzhen? Or is this a pipe dream? What recommendations could you make?
Just living here is easy but there are a lot of expats who live here and are desperately unhappy (see r/China). Most of the people I know that live here and are actually happy do not work for Chinese companies. The differences in corporate culture are significant.
I’d suggest working online as a freelancer or for a foreign company. Chinese companies pay programmers very poorly. Best case would be to build a small clientele before you come.
>My Mandarin is pretty bad as I only studied it off and on for six months or so.
Survival Mandarin only takes a few months and is more then sufficient to get around. How much you decide to learn after that depends on you but fluency is certainly not a requirement. You can come here with zero Mandarin and do just fine- just be creative with a dictionary. Chinese are very patient about these things.
