One of the first books I read about Korea, Korea's Place in the Sun: A Modern History, illustrates the importance of interpreting history cautiously. Korean history, because of the division of the peninsula between two warring countries, is highly politicized. Cumings has been generally classified as a New Left historian and as sympathetic to the North Korean regime. The second charge is just mud-slinging, but the first generalization is still an active question in South Korean politics and academia.
First, since the book's publication in 1997, the Koreas have undergone many changes, both domestically and in their relations. South Korea's media and academic industries have also matured, and expression is more lively and open. There are more generalist and expert histories available on the market, so the importance of Cumings' work is easier to evaluate.
Cumings is generally a proponent of unification. This taints his history in several ways. First, Choson is depicted as a golden age of unified Korean power. Cumings also supports the Conservative Korean line, that foreigners wrecked Choson and downplays evidence of aristocratic factionalism and the weakness of the Korean central government. His discussion of the Japanese Occupation downplays the role of Korean businessmen in the Occupation economy and government. His account of the Korean War is heavy on politics and military leadership discussions, but spare on soldier's recollections. Cumings' sections on North Korean industrialization are competent, but since 1997 the subject has been better researched. Cumings still cannot compensate for the dearth of economic data, which plagues accounts to the present.
Cumings also burdens his account of Korean history with questionable social psychological opinions about the nature of Korean culture. He reinforces the conservative Korean view of the unique mission and origin of the Korean people as offspring of divine forces, a tactic the Koreans share with the Japanese. His account is subtly anti-global and anti-foreign. For this reason, his account is by Korean standards mainstream unificationist, but his open-minded treatment of North Korea notwithstanding, he is aligned with the forces of anti-globalization.
Not that the book does not contain valuable information about Korean history presented with colorful prose. However, what Cumings omits is damning. Most of ancient Korean history is omitted, which accentuates Choson at the expense of earlier dynasties. Discussions of religion are downplayed for politics and sociology. Cumings does not hide his bias, but readers need to examine his opinions well and use his footnotes for independent evaluation. And, by all means, read other newer books about Korea.