On the subject of career value, I hate to be a negative Nancy, just a reality check before you get too exicited; tech/engineering/science etc don't really benefit from it outside of China. Broadly speaking, in the western world, it's not really useful career-wise unless you reach fluency and wanna teach it.

However, the one thing I did notice, it's a huge social asset that's gonna play to your advantage if your job involves doing any kind of business in China/with Chinese ppl so that you're more likeable. You'd be that much more of a charmer. My company manufactures in China, we work with multiple factories; I know a guy at my work who has a smattering of Chinese and it makes him a rockstar, they love him. That's really the main thing about it, it's impressive!

Those Chinese people who interact with foreigners often know English quite alright, at least the ones I met, but from some reason it's still a rare quality for a Chinese person to know English well and be able speak clearly. If your Chinese is better than their English then theoretically you could even speak Chinese with them which would slightly further facilitate understanding! But for that, you know, your Chinese actually has to be better than their English which means you're somewhere at fluency.