History books by journalists are pretty hit and miss. On the whole, history books written by people outside the field run risk of not having arguments at all and instead providing narratives or producing arguments that are ahistorical and drawing too much on sensational claims or fallacies.

Good example of a book written by journalist that sold very well but was panned historians is Iris Chang's The Rape of Nanking. It really publicized the event (in a very sensationalist way) in the West, but it was poorly written from a historical standpoint and lacked very basic sources. Chang's book does include some primary sources in English dealing with the massacre from Westerner's perspectives, so that section could be used in citations, but overall her book would not be used in any serious scholarly work on the subject.

Jung Chang is not a journalist but her book Mao: The Unknown Story (written with Jon Halliday) has also been widely criticized by scholars and historians for giving wrong information and twisting sources for their own benefit.

Some are good, some are bad. It often depends on how seriously they take the enterprise of history. Many are quick jobs that contribute nothing new, and some get many things wrong (a dangerous thing, when they are well-written and popular). Some are serious works of history in and of themselves and are taken seriously by academics. There is no easy way to differentiate them at first glance, hence the need for reviews. The main problem is that the research approach of journalism ("get in and out quick, make it relevant to the reader") can often be in conflict with the research approach necessary for good history ("take enough time to understand the past on its own terms, even if you are doing it because you think it has something to say to the present"). A general rule of thumb: people who can dash off a book on an entirely new topic every year or so are probably not taking enough time with the topic to make a real contribution to the literature, and at best will be just repeating a lot of received wisdom.