Ok so most of this is a copy and paste of an email I sent to my best friend who I play KOF against most of the time.
First off, I love 2k3 though I know it's flawed and all that jazz. I still love the system and the game speed and the combos.
KOFXI is like 2k3 on Crack and they fixed a lot of the dumb stuff from 2k3, though it seems like they added some new cheese to it.
First off, it's like every one is a beast. Well at least everyone I play anyway. King is nasty,
Kim has gone Hyundai and friggin redefined THE KOREAN MACHINE. You can combo his supers, including his LDM super off his QCB+Px3 chains, which combo off of... everything. Hell you can combo his chains, into the regular super, wait till that's mostly done, and then cancel THAT into his LDM super. You can actually do that for tag supers/combos and with other characters in general. Mary is actually really, really good. Well ok she's probably mid tier, but she's no where near as crappy as she was in 2k3, her stuff actually does damage now! Actually I think it's a pretty high damage game anyway, there's a lot of devastating stuff. Almost everything cancels, so much stuff just friggin flows. Kyo and Iori are badass per usual, though Kyo has got some new moves (really old moves back again) and it's pretty decent. Apparantly Tizok is high tier or something, at least a lot of people were using him and he seems to have gotten a few new moves, like one that's almost an auto hit and it's safe to whiff, not too sure how bad it is since I didn't play as him too much outside of MOTW. They fixed his air throw now though, so jumping is just a BAD idea in general against him.
Oswald is the new guy w/ the Cards and it's obvious he's top tier. Though you have to have him as your leader for him to be really bad, his LDM is way too quick and does a ton of damage, while looking awesome to boot. He has some pretty safe chains and some good mind games. They did fix Duo Lon though. Kula is still pretty nasty, though not as bad as 2k2.
I need to go back and try some other characters, though Kim will always be in the rotation, just to get better with him even more. All you need is one crouching A or B or a good jump in hit and it's so easy to chain into his QCB+P varients and then into the supers.
They need this to come out on XBL. This game is 10x better than Neowave IMO.
I should put down some info on my most favoritest KOF bitch eva, King. I've been using her since KOF2k (my first real KOF that I played and got into) and it's so nice to see her stay the beast she was in KOF2k3 after being absent in 2k2.
She's evil, I don't know if she's better or slightly worse off than her top tier 2k3 version but you can play such nasty rushdown with her it's sick.
Jump in with C or D and then manage to get a close standing D, from there you can cancel into her sliding kick (df+D) which if you cancel into that from a combo you can cancel out of it into.....
Her backflip super (I think it's QCBx2+K)
Her standard rush-in super (QCB, HCF+K)
A Trap Shot
A Double Kick
A Venom Strike
And if your opponent is trying to play keep away from her it's OK because she can be a fireball WHORE. She still has the low Venom Strike fireballs (hits low), she has the double strike 2x fireball move (mid hit, classic style), and she has the high hitting one too that acts as a decent anti air if you anticipate it right. Works well to throw a few double strikes or a low strike or two and then throw a high one out to catch them as they try to time a jump at you.
There is almost nothing she can't deal with.
I haven't done too bad for myself out here on it, even had some guy I beat a few times come to ask me how long I've played.
It's like they don't expect foreigners to do well when I was playing this and 3S out in the arcades I always seemed to get people who stopped to watch when I got on a winning streak.