Viking's Undiscovered China only goes from Shanghai to Beijing and we also did the Hong Kong extension. The entire trip was wonderful and our escort, Francis, couldn't do enough for his 38 passengers. As other reviews have said, the escort is with you the entire trip (a different part-time escort was in Hong Kong). The escort is your main guide (some local guides are also used) and a great help with any trouble shooting that you need. We are generally independent travelers and even when we do a cruise we will go off on our own, but not in China.
The ship did have some dehumidifiers running in the halls but we didn't have any problems with the humidity. The weather was generally cloudy and we did have some periods of drizzle or rain; but it didn't interfere with planned activities.
All of the hotels were 5 star and the food was very good. On the ship the breakfast and lunch buffets had plenty of options and for dinner you could order from a menu. Wine and beer were included with lunch and dinner. On the land portion of the trip, lunches were always Chinese food served on a Lazy Susan and some of the dinners were buffets. The buffets were better because they generally had some Western food and more variety.