in JK1 MP, when u pinged ur opponent and ur ping to him was 600, then his ping to you would also be around 600. In JK2 MP it doesnt work that way anymore. You ping urself to one central dedicated server. This is excellent for gunning, u see ur opponent where he actually is= u can now actually aim at ur opponent and hit him, instead of having to "predict" and aim 4 feet in front of him...
Just an example:
You have a ping of 300 (which would be good for JK1 lol), your opponent has a ping of 50. You get in a gunfight with ur opponent.
You're both shooting, but you had him in ur crosshair first and u started shooting first. Your aim is good, you can't miss, you started shooting first, you both have the same weapon and same health, so you expect him to die first.
That doesn't happen: You die first and he lives. That's because his bullets were recognized sooner by the server, because he had a lower ping.
You might think: ooh, that 0.25 second difference isn't important, but these shootouts happen very often, and u will die a lot just because ur opponent has a better ping. After a while, that becomes incredibly frustrating. You know u have better aim, better moves, better reflexes, but he has that 0.25 second difference that makes u lose.
Now when u join a server with ur 56K and 200 or higher ping, and everybody else on that server has a bad ping too, then it's not such a big problem...
But when u join a server where everybody has broadband connections and a ping of 50, then ur the one with one big
oh well.. JK2'll still be playable with 56K, but those people will just have a big disadvantage when they're on a server with all other users having low pings.