I read it too. An amazing, well-researched, and, as you said, a difficult subject. Before I read it I read The Mysterious Numbers of the Hebrew Kings (Edwin Thiele, See here). This also was a difficult read, but well worth the effort. (And I think Thiele is passed now, but I am very grateful for his 30+ years of research that he put into his work.)
When I first started lurking here I saw all the hubbub about 607 and was inclined leave that subject for others. As I continued researching (outside WT parameters) I began to see the need to look into this subject. So I read Thiele's book first, then Jonsson's. The two books unintentionally form a complimentary pair. Thiele is interested in establishing the dating of the Hebrew kings from the split in the kingdom after Solomon (c. 931 BC) down till the last king (Zedekiah) and the fall of Jerusalem (c. 587 BC). So Thiele is more interested in the whole chronology, while Jonsson is intent on dating of the fall of Jerusalem. Yet their seperate research meets at the same point in time. The two books left me with no doubt about the true dating of the fall of Jerusalem, and more than ready to explore the impact that had on my WT understanding of things.
Take Care