Many historians and scholars throughout history have asked, "How reliable is Josephus' work?" Let's consider some of the arguments.
Josephus commonly exaggerated, embellished, and overstated his writings. Some historians point to the fact that he was overstating for dramatic purposes. For example, he says that so much blood was shed in Jerusalem that streams of gore extinguished the fires that burned. Although this is exaggerated, his point is clear!
Josephus is not consistent with numbers. For example, he says Mount Tabor is "thirty stadia" (18,200 feet), when in reality the mountain is only 1,920 feet. Exaggeration of numbers is very common to authors of that era.
It is also thought that Josephus' wrote highly about his exploits in order to enhance his image. His endeavors are not always written consistently between written works.
"In behalf of Josephus, it must be recalled that all these defects…were widely shared among ancient historians, few of whom brought critical tools to their craft in any modern sense. Josephus, in fact, was more reliable than most historians of his day. Whenever he is not referring to himself, his material is basically reliable."1
Details of geography and architecture of that time, which are stated in Josephus' works, are being verified today.