If your experience of travel writing is mainly the likes of Bill Bryson, Tony Hawks and Michael Palin, this is something totally different. Colin Thubron is almost intimidatingly intelligent and perceptive. He does not patronise the reader but assumes you are as intelligent as he is, and he wants to share what he is seeing and hearing. As he speaks many languages and seems to have the gift of picking up a little of each new language as he hears it, he has a lot to report, and he does so clearly and accurately (so far as I can tell). There are few, if any, of the "humourously colourful locals" found in other travel books, partly because I think Thubron respects people's dignity too much to laugh at them in this way. He is, perhaps, part of a previous generation of travel writers, which I do not consider a bad thing.
Like the best travel books you will learn about the geography and topography of the areas Thubron travels through, you will learn something about the locals he meets on his travels, and about the history of each place he visits as he passes through. One revelation for me (perhaps others were already aware) was that the silk route was seldom travelled from end to end; most merchants traded with the next towns in each direction. It was through a relay that goods passed from merchant to merchant, from Antioch to Beijing, and beyond in each case. Thus the Romans in the West had no idea of China, while the Chinese had no idea of the Roman empire. By the end of the book the reader will have some idea of both cultures, and those between. You will also have some idea of the people on the silk road today; they may not be what you expect from those countries.
A journey with Thubron through the medium of this book is a delight, but you will need to think at times. A journey at his side in reality might be stressfull because I would worry about falling short of his expectations of me. I would still sign up tomorrow.