Resident Evil 0 was a very enjoyable game, in my opinion. The few major changes made from the original Resident Evil on Gamecube (that I noticed) were: 1) updated and gorgeous graphics - I couldn't believe my eyes when I saw them, 2) the ability to drop and pickup items whereever you please, and 3) the ability to play as two different characters.
I liked the 1st and 3rd changes that I mentioned, however, I don't know how much I liked the 2nd. Often I'd find that I need to backtrack in order to get some item that was annoyingly far away. In the first, there was always "happy room" (that's what I call it, because it has peaceful music) that wasn't too far away, and those always contained those chests that held all of your stored items.
The music in Zero is great and adds to the games creepiness as well.
Overall I'd say Zero is worth your money, especially now that's it's cheaper. My score - 8.0