When I first headed to China in 1985, the only guide to the country's birds was a (then) recently published volume by museum man Rudolphe Meyer de Schauensee, who reportedly figured he could learn all he needed about the country's birds from his specimens (in the US), without visiting China. This had a fine introductory chapter on the history of ornithology, including tales of derring-do by Russian ornithologists risking and occasionally succumbing to bandits and diseases to collect specimens including species new to science. Yet, the field descriptions were sadly wanting (honey buzzard has feathers on the head and throat "which are short, stiff, scalelike and very dense"!) The plates were poor, omitting many key Chinese species - presumably as the artist could only portray available specimens.
Against this, A Field Guide to the Birds of China by John MacKinnon, with illustrations by Karen Phillipps (Oxford University Press, 2000), is a major improvement - as it should be, given John MacKinnon has extensive field experience in China; Karen Philllipps lived in Hong Kong. Notably, most of the over 1300 species are illustrated in colour (some only in black and white, accompanying the text).
But here too, the descriptions are often casual and cursory. We're not quite at the level of having to touch the heads of passing raptors, but some of the tough birds like warblers might not be described with too much more than "medium-sized, brown": works for readily separated species, but when the identification gets tough, well, Birds of China doesn't get going.