i didnt think world 5 is as bad as most people seem to think. part of that may be that i went there last and was therefore a little overleveled for it, but especially 5-1 isnt that annoying. 5-2 is a little, but i still think the antipathy directed towards it is a little unfair.
Adjucator shield + blessed weapon and that poison is no longer annoying in 5-2. You can also find the regenerating ring there which helps a lot.
5th world is my favorite in Demon's Souls despite the bosses are pretty easy. The atmosphere, level design and the loot there are so good.
We don't see places like that very often in video games.
I love that level.