It's also worth pointing out that 2E has some of the best supplements put out for the game, ever, in the form of the revised Realms of Magic, the Tome of Corruption and the Tome of Salvation (as well as fun smaller supplements like Renegade Crowns).
On the other hand, the earlier supplements in the 2E line are, to my mind, of a lower quality. I'm not enough of an equipment-jockey to want the Old World Armoury, so I can't comment on it, but Sigmar's Heirs and the Old World Bestiary seem mainly devoted to covering material which should have been in the main rulebook. (Indeed, the 1E core is essentially the 2E core, plus the Old World Bestiary and Sigmar's Heirs, only it's lumbered with a crappy magic system), whereas I found Knights of the Grail to be pretty useless.