@masterrain: Taken as a whole "world" (to use a Demon's Souls term) as it were the DLC in Dark Souls I is definitely the best part of the game, 4 of the best bosses in the series. Is Anor Londo still better individually? Debatable but for most people sure, however it's not really comparable as Anor Londo is a much shorter area on a linear route. It's certainly much better than the Catacombs and the Painted World.
Yeah as a world, Artorias was very solid. From a pure gameplay point it was quintessential Dark Souls. However I quite like the discovery aspect, maybe even more than playing! Although it was cool descending down to Manus, stuff like the Catacombs and Painted World were just more intriguing. Anor Londo was just a massive wtf moment, so mysterious! I'm enjoying Ivory Crown a lot as it has that unknown aspect, Iron King had it a little too. That's why DS2 was a bit disappointing for me personally, just seemed like lots of cool levels with very defined start and end points, rather than exploring a world.