Too Much Detail, Not Enough Analysis
I've read several volumes of the Longman History of Russia and this is the weakest so far. Russia in the 13th century was divided into a dozen principalities with competing rulers, and the Mongol invasion added another layer of complexity. But this book fails as a guide to a confusing era. There are several problems:
a) There's entirely too much detail about all the petty, and ultimately pointless, struggles between the various Russian princelings.
b) As a consequence, there's no space left to discuss the economy, culture, art, or religious life of the period.
c) There's little analysis. And what analysis there is seems to be tacked on, rather than to grow organically from the events described.
d) Finally, the book was originally published in 1981, so it's getting dated.
I definitely don't recommend reading this book for pleasure. Unless you really, really want to know every detail about the doings of the princelings of the Rurikid dynasty.
For what it's worth, the two other books in the Longman History of Russia that I've read, "The Emergence of Rus" and "The Formation of Muscovy," didn't have the problems I mentioned above. (They can be dry at times, though.) I'd give both of them 4/5.