When this first came up on my radar I ordered a copy, and posted the link on two Yahoo groups, which are devoted to British and American dance bands respectively. As you can imagine, the members are pretty well clued up, as a result of which I heard there'd been such a rush of orders that the distributors were having to restock. Nevertheless, I'd be falling short as a reviewer if I didn't note a couple of reservations, so let's get them out of the way first.
As is not uncommon with Membran 10-CD boxed sets, the tracklist is minimal. That would be tolerable were it accurate, but sadly it is peppered with factual errors. For example, two titles show a different tune from that on the CD, one track is featured twice on different CDs, several tracks date from the 40s, and details of vocalists and composers are not always accurate.
Despite those caveats this is a real bargain, best described as a random set of recordings by British and American dance bands, peppered with a quite high proportion of outright jazz numbers, several of which are extremely rare. My advice is to snap it up whilst it's available.