I bought the gift set and my players each bought a player's handbook without complaining, which was a first ("too much money!" et cetera, et cetera).
Buying the Fourth Edition books also inspired me to start buying books of the older editions too. Not that that really means anything.
But all the local book stores seem to have sold them out pretty fast. Or, sold out the PHBs, anyway. My local gaming store was out of PHBs for a long time, and after it came out they sold out of the Adventurer's Vault and Dungeon Master's Screen pretty fast too. They're well stocked on modules, though.