i recently got a ZI, in black
) i had to wait a while until a black one showed up on ebay, and as far as i can tell i paid a slight premium for it.
with regard to focus, i find it to be very quick. i haven't used a contax or hexar, but i use canon dslrs regularly and haven't felt like the AF on the ZI is a problem. i just put through my first roll using AF and haven't tried manual focus yet, so i can't comment on that.
like dan, i like the native vertical because it helps see things differently. i've had no problems at all shooting horizontal, the camera is light and easy to hold because it's so big.
i'm actually still waiting for my first roll to come back from developing, hopefully all of my horizontal shots aren't messed up and my shots out of focus, lol.