NO no no DamagedInc please FINISH THE GAME FIRST. Please.
I kind of did not like the 2nd part of the game as well - due to warping it lost a lot of its mysticism? and challenge?
But for me it is hard to pinpoint what exactly is the 2nd half of the game as I went straight to the end of Tomb of Giants, to the yellow fog door, waaaaay before even visiting Anor Londo. The same with New Londo Ruins - you can kill the Red Sorcerer and kill the boss without ever visiting Anor Londo. For me that was still the "1st part" f the game aka AMAZING.
Duke's Archives are kind of weak... I did not like them at all. Crystal Caves were awesome. Everything that is past the yellow fog door in Demon's Ruins is GARBAGE so yeah, the real 2nd part of the game aka Lost Izalith and Duke's is objectively speaking worse than the 1st part.
So to recap from MY playthrough (before getting Lordvessel):
1st part:
Undead Burg, Undead Parish, Depths, Blighttown, Great Hollow, Ash Lake, Darkroot Woods, Sen's, New Londo Ruins, Catacombs, Tomb of the Giants, Demon Ruins, Anor Londo --> all incredible areas
2nd part:
Duke's, Crystal Caves (exception), Lost Izalith, Klin --> much, much weaker than the 1st part