Everything about this game has already been said. But, I always have something to say anyway. The game is sexy.
What saves this game from being at most mediocre is the character evolution and customization option. It's really fun to pick your favorite characters and modify the way they look, what weapons and skills they use. The game gives you the tools and a whole lot of equipment to choose from (once you unlock it). But it's not only fun, it's also useful, because by customizing a character you can make them better, and beat arcade mode or The Tower of Lost Souls easier. Really there are so many options that you won't get bored with this for a long time.
And here's when another cool feature jumps in: Character Creation. You can create your own character from scratch. And this time it's not only altering something you've already been given, you can build your fighter from the ground up, including creating a unique physique (you can't change the physique of existing characters). Basically Character Creation is the most fun thing about this game, in my opinion. Only one thing is disappointing: you can't create your own fighting style, you have to choose one of the game characters' style. But to be honest, I think creating a whole new set of moves and assigning them to buttons would take far too much time to be worthwhile. So it's both a bit disappointing and a good thing at the same time.
Another thing that has to mentioned is that there are various single player modes, which also save the game from being mediocre. In addition to the story mode you have the Arcade Mode and the Tower of Lost Souls mode. The latter is basically a survival mode in which you have to first ascend to the top of the tower by defeating all enemies on each floor. Once you've reached the top you can choose to descend and see how many enemies you can beat. The thing that makes it different from normal survival modes is that on every floor there is a hidden treasure chest which you can aquire by fulfilling the floor's task. It can be anything, really, from things like performing a throw attack to pulling off a critical finish (which by the way is almost impossible in most cases, because you always kill your opponent before you can make the move).
To wrap it up, Soul Calibur 4 is a very solid weapon-based fighting game. All the unlockables and character altering make it shine. Not to mention the fact that the game is very pleasent to look at. Maybe it's not the best word to describe a video game, but... Soul Calibur 4 is a sexy game. 8.0