We opted for the longer cruise and would probably opt for the shorter version knowing what we do now.
The ship is fine, our room was a spacious "Junior Suite" we were with friends who had one of the very large "Explorer's Suite" it was wonderful with wrap around windows and decks. Though we've only experienced much larger ships with many more amenities this ship had many places to go and do things.
The dining room was at times loud with the engines as noted in other reviews. The food was rarely good, most everyone complained and often sent theirs back. I found the always available salmon to be reliably excellent and my partner often ordered pasta with mushrooms which he liked.
Its true that the crew is extraordinary and they remembered so many of our names, Lois was a standout. The Viking system of keeping 30 some tourists together with one guide works very well and the guides work very hard to make sure everything goes according to plan, ours even wrote his cell phone # on the back of all of our name tags in case there was an emergency (this worked well for someone who got lost on one excursion).
Beware that Viking says you are allowed a max baggage of 44 lbs but never mentions it also must be one bag only (all four in our group had 2 bags each with total weigths under the limit but we were charged for the extra bag when we flew on the extension to Hong Kong)
Viking booked us in to fantastically luxurious hotels, the Regent in Beijing was the most outstanding.
The downside was how dirty and polluted the cities and river were for the cruise portion, many of the docking situations are pretty ugly (even if you go out to see something wonderful away from the boat)it can be smelly, dank and grim.
The extra extension to Guilin has one of the best highlights of the trip, a cruise down the gorgeous Li River - this is amazing, beautiful, clean and serene through one of earth's most gorgeous places - a great departure from the somewhat rushed hustle bustle of most of the trip.
Its a trip well worth making but it does incorporates many highs and lows due to the nature of China itself. I recommend Viking, as others have mentioned this would be impossible to book on your own and you will see a lot in a short period of time all while being "handled" by capable staff.