Seconded. I spent 8 weeks in 2006 hiking up the Yangze River. My advice: pack light. One camera, two lenses 28/50.
And avoid the hotels. Stay in hostels. Very cheap, very abundant, and it'll give you a much better chance of meeting other people who can tell you of great plces to go. You'll also meet more locals because you wont be the the hotel cacoon all day.
Take buses and trains. Go 3rd class on the trains. You'll be with the locals. Also, seek out Buddhist monesteries in the hinterland and stay there.
Bottom line: avoid the standard tourist cacoon and you'll have an AMAZING time.