I've been playing 1e, 2e, PF, 5e and most recently B/X. I fell in love with the simplicity of the rules and bought the original books, but they were a bit clunky for use at the table. I jumped on these when I saw the print version was on sale and I'm so happy I did. It's great that each booklet covers an important topic and centralizes and condenses the information from both Basic and Expert rules.
The print quality is great; the illustrations are simple and really capture the old-school feel, without taking up too much space or hampering readability. Also, something that I did not expect was the size of the printed material; it's very handy and won't take up much room on your shelf or at your table. I'd think of them like a set of field manuals and I'd say the size is a plus: they aren't as cumbersome as a full sized book but the small format doesn't affect readability at all.
I wish I had these books when first introducing my group to this system, I think the booklets will help clear up ambiguity and confusion that comes with an unfamiliar system. These books will definitely be on the table when running our B/X sessions; I might buy a second set just to have at the ready.