This product is best served as a reference for someone wanting to run a campaign or adventures set in the Impiltur region. It is basically a region specific slice of Grand History of the Realms, with some new lore and vignettes. For that reason, it is best suited as a reference only. The writing in the vignettes is good, but I didn't find them particularly insprising in terms of ideas for a campaign of my own.
George Krashos is a well known and well regarded Realms historian who has written for Dragon several times so this is good, authoritative work. I think the way this work would be better is if it gave a little bit more DM's instruction as to good resources for general Impiltur reading to give better context (beyond what is in the index).
Regardless, for free (I beleuive the work is already avaiblable for free at Candlekeep.com), this is an awesome product.