I just returned from this trip (May3-16). We booked the trip with little research, based on our positive experience with Viking in Russia last year. We were not dissapointed. Great people, great shopping (and we are not big shoppers), good food. Tour organization, transfers and guides were excellent. We did not book the extension in Shanghai and found ourselves wanting to return.
Fire away with any questions you might have. We had a great time and would be happy to share.