My old Cook and Morton has about 1,500 pages with about 10 records per page ,so this 1,000 recording job is very slimmed down indeed. It was the comprehensiveness of C&M that did the trick for me, so I won't be getting the new one. As Bev says, a useful starting point for someone new to jazz.
While we're talking about jazz tomes, has anyone come across The Virgin Encyclopedia of Jazz ed. Colin Larkin? This 1,000 page item costing £40 was bought for me by colleagues as a retirement present 11 years ago and has certainly stood the test of time. It's arranged biographically in alphabetical order, with about 4 artists per page. At the end of each artist entry is a surprisingly comprehensive list of recordings. In the 11 years I've had it, I've brought it up to date by pencilling in the dates of death of those who have departed since 1999 - a sad duty. You won't be surprised to hear there's hardly a double page spread without at least one pencilled date now.