Better balance, better plot, better atmosphere, more polished, more original, fewer useless gimmicky items, no cheap deaths, no backtracking, no fan service, better pacing, more viable character builds, better pvp(from what I hear. I never did much pvp), better implementation of risk/reward mechanic, better voice acting, better characters, cooler bosses/enemies, less faggy looking armor, less faggy looking weapons, and just all-around better in almost every imaginable way. The only things I would change about Demon's Souls are ladder slides and load times.
Thoughts, anyone?