Kratos:He's ruthless, tough, never gives up (he's died twice already), and he kills GODS. How much better can it get...

Then...

Solid Snake: You've gotta give the guy credit. He does a LOT of SHlT in MG2, helps people he doesn't even know (the russian woman) and a whole lot of other stuff i can't list due to lack of space.

Kennedy: I think he isn't PS2 exclusive but he still deserves some credit.

I've played both, and i can say that the 2nd one is better. The graphics are impressive, almost the same as in GOW1 but some scenes are sweet. Also there are less frustrating parts, but the damn blade traps are still there. If they were 2 seperate games I'd reccommend GOW2. I hope this answers your question.

But...

since they are directly related, take my advice and DON'T PLAY THE SEQUEL WITHOUT KNOWING WHAT HAPPENS IN THE FIRST ONE.