The Contax is to 35mm rangefinders what the Fuji GA645 series is to medium format rangefinders...they're both auto-everything cameras that you must learn to trust, but that will reward you with great results when auto-everything is good enough. (In both cases you
can manually focus and set the exposure yourself, but you really won't want to.) If you want a manual 35mm rangefinder that doesn't break the bank, consider the Voigtlander Bessa cameras. Plenty of people are very happy with them. Personally, I use an SLR when I want control, and the Contax when I'm willing to let the camera do most of the work.
I have a Contax G1 and haven't had any focus problems. The most common complaints are about the 90mm lens on the G1, but I've not run into problems with that combination. Both close up (head-and-shoulder portrait) and at a distance, the lens has focused well for me.
The "holy trinity" of lenses for the G series (the 28, 45, and 90mm) are absurdly cheap and are excellent performers. The 21 and 16mm lenses are too pricey to tempt me (although that 21mm does sing a Siren song...). The 35mm is reasonable, but too close to the other lenses to catch my interest...it might be the lens to buy if you're looking for a one-lens kit. If you want to get something strange, Zoerk actually re-mounts the Voigtlander 12 and 15mm LTM lenses into Contax G lens barrels. I'm sure the 12mm would be a fascinating lens to play with, but again these lenses are pricey. Finally, if you have the G2 you can consider the zoom lens, although I've never read a positive review of it. (I suspect that has as much to do with the high image quality of the prime lenses as with anything else.)
I'm off to Paris in early June, and the Contax will be my travelling companion. I've been to Paris numerous times and have shot plenty of manually metered images on larger film...this time I want to spend more time looking at the city rather than at my equipment. I expect that the Contax will perform as well as it always has.
As Tim notes, look elsewhere if you want a camera that you can control. Beyond simple things (choosing your own film speed, setting exposure compensation) it's best to allow the camera to do the work for you. Manually focusing the G1 is a nightmare, and I've read that the G2 is only somewhat better. There is a manual for the G1 online at
http://home.comcast.net/~samius/CONTAX_G1.pdf - a quick scan through should give you a good idea of how the camera works. (I don't know of a G2 manual online.) The one thing you won't get from the manual is the feel of the camera...these things feel wonderfully solid when you hold them.
Best of luck.
Dave