[majimojo]

I've done four years Japanese. 1-2 years Chinese + 3-4 months immersive Chinese at Beijing University. My chinese is way better than my japanese, so immersive study definitely works. Chinese is very hard because it works on tones. In English and Japanese, you can put the emphasis on the wrong syllables or speak in a monotone and still make sense. In chinese, not using proper inflections makes you say something else.

1 year will get you through every day life, but trying to communicate on a business level or even listen to the news on TV will be very difficult. It's possible to be fluent enough to do business in 2 years but you'll need to get a Chinese girlfriend. After 3-4 years you'll start to lose the "accent."