Soul Calibur III takes what was great from Soul Calibur and Soul Calibur II, but sadly, that's about all it consists of.
The plot is a little different than before, but it is virtually the same plot as its predecessors. Soul Calibur III adds nothing new in terms of gameplay -- but that isn't necessarily bad, because one of the things that was awesome about the Soul Calibur series, is the fact that the combat was always fun and easy to pick up on, but in - depth. It is a disappointment because it really doesn't add anything new to the series except for the usual new characters, stages, music, and a single player story mode separate from the arcade mode. The developers also through in a character creation. It's very simplistic. You unlock clothing by playing through each character's story. You can buy new classes, weapons, armor, and other things, through the shop. There is also the gallery where you can view trailers, concept art, etc.
The new single player mode is called Chronicles of the Sword. In this new single player mode, you use a character from your character creation to play through a story separate of that of the main arcade plot. You start out a rookie in fighting, and you become stronger, and more respected as you play through each level or battle. It's a neat addition in which you can travel on a map and become a general of an army, but I was unable to experience this mode because of the memory card corruption problem with the game!! That is very frustrating because it prevents me from further unlocking the game's contents! Another letdown with this installment is the lack of online play. It would be nice if you could take your created characters online instead of just using them on Chronicles of the Sword. The next Soul Calibur game will most certainly have online play.
All in all, Soul Calibur III adds practically nothing new to the table, but the game is still great because it holds everything that makes the series great. If you haven't already, check out Soul Calibur III, especially if you haven't even looked at the series before.