I finished reading it yesterday, and the best I can say is that it is a mixed bag. On the one hand, I think it's a decent overview of the Middle Ages...but on the other hand, it's only a decent overview of a specific aspect of the time. The author focuses almost exclusively on the political world, barely spending any time on other facets of medieval history.
Another thing: his writing style is incredibly tedious. At times the subject matter was fairly compelling, but rarely was his presentation. This may be because the work is a condensation of a much larger one (The Cambridge Medieval History, which is 10 or 11 volumes); it may be a reflection of the fact that P-O died before completing it, and consequently the text may only represent an early draft of his intentions. If this is so, then the editor must share at least some of the blame for not cleaning it up. The syntax is pointlessly muddled quite often.
If you can stand to wade through it, it's a decent survey of the politics of the Middle Ages. But if your interest is more in the way of the arts, or culture generally, then you may as well skip this book. You won't find much here to compensate the effort spent in reading it.