I recently started playing/GMing Pathfinder (beginner rules) and currently shopping around for the Core Rulebook (planning ahead). The way the PRD puts it, it sounds like the Core Rulebook is entirely unnecessary:
This compendium is NOT the official Pathfinder Roleplaying Game! Players interested in a user-friendly introduction to the Pathfinder system will want to purchase the complete Pathfinder Roleplaying Game Core Rulebook and the Pathfinder RPG Bestiary, which comes complete with more than 350 monsters to menace your player characters.
Both books contain hundreds of beautiful full-color illustrations and lots of descriptive text to explain and introduce key rules concepts necessary to fully enjoy the Pathfinder Roleplaying Game experience. (source)
I do enjoy reading their "user-friendly" material, but if all I'm missing out on is wordiness and pretty pictures I have no problem at all with that and saving $30-$50.