Alex let us know that CS: CZ is basically a single-player FPS that utilizes Counter-Strike version 1.6 as it's online component.
Personally, I rather enjoy version 1.5 of CS -- not 1.6 -- so, I am not sure if I will bother picking up Condition Zero. I just don't have the desire to play a single player FPS. I enjoy the challenge of actual players, online.