What do you mean by good or bad? Are you looking for maintenence answers, or how reliable they are, or just general opinions as to what we think about the 500? Check out this thread: S-Class Fiasco: W220 vs W140

Its a long thread about the W140 S-class vs the newer W220 S-class, they talk about many subjects, and a lot of owners with W140's replied. Hope this helps.