I find using VNAV PTH in China can be a very labour intensive operation. In fact I could probably say that about any descent to an airport in Chinese airspace. At one particular airport we go to it is not uncommon to be denied descent clearance until 10 or 20 miles past TOD, and then have to descend with a 50 knot tailwind and try to regain path. All this from a cruise altitude of 22600 feet, so large speed reductions prior to TOD are generally the order of the day.
Other places are the complete opposite where they will have you descending sometimes up to 150nm prior to your normal TOD and telling you "descent rate more than 2500fpm".
So the opportunities for using VNAV PTH for descent I find are very limited but when you do use it you have to watch it very carefully and be prepared to change modes or fly manually at any time.