Compared to the 4 previous 5e monster books it is pretty haphazard, some monsters are place alphabetical, otheres grouped by type so.e a little of both. Which in my opinion ruins it for actually using the book to play the game.
All 3 of the new core books suffer from changing things, but not really fixing anything when the books as a whole are considered. They may fix a few things but break things that were fine in the books they replaced. The 24 core 3 are at best a lateral step, definitely not a step forward for 5e. It's feels like several groups set out to make the books with different views on what they shoud be, and they ran out of time before they could bring all of those ideas together in a polished final product. The new books are different from the old, but they really aren't better books.