A year-by-year, later day-by-day, chronicle of the war against Sauron from the founding of the Shire to the glorious conclusion seems at the outset like a good idea. Perry calls LOTR's Appendix B, the Tale of Years, "far from complete" but it covers the whole period: what he means is that it's not detailed enough for him. Appendix B won't tell you which day Sam cooked coney for Frodo; Perry will.
But alas, the book does not stop there. The entries are written as bullet lists like a PowerPoint presentation, and many add pointless little flowcharts such as two-generation family trees. They reduce Tolkien's magnificently complex subcreation into a giant mass of undifferentiated trivia. And each yearly or daily entry comes with its commentary, whether directly relevant, side points, broader considerations, or dogmatic essays in applicability. The unrelieved banality and inappropriateness of these must be read to be believed; as also the author's clumsy, grammatically inept style, and his smug superiority to the characters. (He frequently criticizes the good guys' "blunders," all of them more complex than he implies.)
There's actually some good chronological analysis and speculation hiding in here. But how can someone who knows his Tolkien that well say that the wizards were Valar, or that Rohan gave Isengard to Saruman (it wasn't theirs to give, and Saruman was made its warden, not a freeholder), that Boromir and Faramir had a sibling rivalry (Tolkien specifically says not), or suggest that Galadriel should have sent daily eagles to check up on the Fellowship?
These are not isolated examples: the bloopers and misconceived ideas go on and on. The whole book is like that: it has the soul of a PowerPoint presentation. I can't recommend it on any terms.