KK2000 plays like a no-nonsense, yet full-featured interpretation of boxing. If you've ever seen it in the ring, you can probably do it in the game (with the exception of having some idiot parachuting into the ring and, thankfully, the patented Tyson-ear chomp).
I agree with Chi here, in fact there isn't much I can find to disagree with. The legendary boxers are represented here much more faithfully than in the N64 version and the extras on the disc (boxer bios and 'classic fights') are pretty slick and are welcome additions. As Chi mentioned, this version is much more of a simulation and those of you who read my N64 review will know that the lack of this feature was mostly responsible for my low overall rating.
I can't disagree with any parts of Chi's review. As arcade boxing games go, I really thought only Nintendo could effectively create unique and oddball boxers in a great playing boxing game, but in this case, Midway has done a superb job in matching Nintendo's best efforts.
Through wildly imaginative characterizations that has more personality than Don King hyping his latest promotion, Rumble makes it easy to forget all the technology in favor of a vivid boxing microcosm. Rumble is a world that comes complete with heated ring rivalries, larger than life egos, and trash-talking bravado worthy of Mike Tyson after one of his 'patented' first round knockout (remember those?).
Knockout Kings 2000 lacked damn near every-thing I saw in those legendary fights with the exception of the fighters themselves. The feel of vicious punches was missing, the characters moved too slowly, and none of the fighters distinguished themselves. Whatever was in the game to add realism was negated by the over-the-top arcade elements. The only true representative from the boxing world was Mills Lane (how sad is that?).
From the early goings, KK2000 has a lot working against it. Primitive looking models, mediocre motion capture, and poor collision detection all seemed to spell doom for KK2000.