Hello
I'm a French Software engineer and I've been working in China for 5 years (and now back in France)
As someone who has worker in IT both in the education part (I was teaching CS in a 3 tier small city of 4 million inhabitants) and a startup/webshop in Shanghai I can only recommend you to try the experience.
As other have said life there is extremly different. If you're in Shanghai/Beijing, you can still find places to eat/live that will make you feel like home, but I think it's missing the point.
I would say the more you're ready to try to "mix in", the bigger the opportunity will be. I finished with a near fluent Chinese fluent level (I can perfectly follow business and informal conversation, and get the rough meaning from written contract in Mandarin) and I think that's what definitely helped me to finish CTO of the company I was working in. (~60 employees, 99% Chinese, doing businesses with other Chinese companies)
Chinese is a very easy language once you've stopped trying to relate to English and you see start seing learning chinese as gathering "sentences" and speaking Chinese as "i take this sentence I heard last time and I replace this word by that one" (as there's no conjugation, plural etc.) and it will definitely helped relationship of any kind, especially if you look "foreigner"
On the technical side, speaking chinese will help you enter in the companies were people still do php4 without framework nor testing nor versionning (SVN if you're lucky) because there's no harsh competition. So arriving in this kind of company with your ability to bring them even what you would consider "plain old MVC framework" will increase their efficiency by several times. (and if the company was there, it's that it was profitable, most of the time because of the manager/commercial having a good network, so if you're now able to make technical side profitable too, they will soon ask you to supervise/teach/manage the whole set of developers). And you will be invited to meeting with the customer too as it will give face to the company "hey we're a good company, we can hire laowai foreigners".
There's a lot more to say but I think most of people here have already covered the other aspect of living and working in china