I'm Beta testing the mutliplayer now, and there are no frame rate issues at all. There were frame rate probs in the Alpha which I played at E3, but not in the public release Beta. Whoever is claiming there are frame rate issues is full of BS.
Servers support up to 16 players, and I have played 16 player Death Match, 16 player Team Death Match, and 16 player Assault.
Controls feel closer to TimeSplitters 2 than they do to XIII, which is good, and gameplay is a cross between Half-Life and MOH: Allied Assault. The Dev team told us that there will be keyboard support for chat at launch, and I believe headphone support as well. Weapons are more realistic than fanciful.
Graphics are hi-res for a PS2 title, and far grittier than the pretty Halo. Comparing the graphics of Halo and KZ is like comparing the graphics RE and SH -- both titles are survival horror, but both are very diff games and take very diff approaches. Techincally Halo has a higher resolution, but KZ still looks comparable -- it includes lots of texture variety, and looks very detailed.
The maps in the Beta well designed -- a beach head, a train station, and a jungle. Environmental sounds are plentiful -- bugs in the jungle, and inner city firearms in the distance on the train level. More levels will be available in the final release.
There are a couple of flaws in the Beta, that are scheduled for fixing -- including things like everyone's name appears over their head in non-team DM, or that when u pick up a weapon sonetimes you fall forward thru the floor. There are a couple of other small probs, but I have read that all these issues are scheduled to be fixed. Nothing is earth shattering, though the names over the head prob in non-team DM is a big prob in my opinion.
Load times are pretty decent, like any other FPS game on console or PC. Gamepad control feels natural, like TS2, and I don't find myself wishing for a keyboard and mouse like I did in XIII.
The multiplayer portion of this game will be a success, without a doubt -- the only downside is that it does not use the HDD for downloadable maps, which is great if u r a cheap ass ;-)