Hi, peatiscool,
I can only talk about the T3 because I am not familiar with the Yashica, exept to note that the T3 has a non-zoom 35mm lens, while the other is a zoom. My preference is for the non-zoom, because for me, it is more important to have the faster lens; I do a lot of shooting in low light, and I like, at least in theory, to blur my backgrounds.
The lens on the T3 is wonderful, as good as any SLR lenses I own. I have no hesitation using this camera instead of my SLR, at least when I am shooting moderately wide. The body feels good; it fits nicely in a jacket pocket, although its weight for its size may surprise. For a compact, it has a lot of manual override. You can set an aperture and have aperture-preferred exposure. It will give you an approximation of the shutter speed you are at. You can also pre-set the focal length, and if you spend a little time learning about depth of field, this can make the camera very quick to work with. It is also has a relatively quiet shutter and winder, making it pretty good for candids. There is also exposure compensation which you can use for backlighting, for example, or for shooting at a different ISO than the rated one.
The downside. It is very expensive. Also, there is a known flaw in the winder mechanism, which may result in your having to send yours in for repair. I need to send mine in. Unfortunately I bought mine grey-market and have to figure out where to send it. If you buy in Britain, I would recommend Robert White, an authorized and respected dealer.
The T3 is the end of the evolution of the compact film camera. It's not perfect, but with the advent of digital, it is highly unlikely Contax will make an newer version.
With the exception of the Train Cemetery picture, all of the shots on page one of my Bolivia gallery
http://www.pbase.com/zuiko40/bolivia
were shot with the T3.
Speaking of which, if the price of the T3 doesn't scare you, and you want a Zeiss zoom, and digital, you mght want to have a look at the Sony T-1.
There is a review on Luminous-Landscape.com.
http://luminous-landscape.com/reviews/cameras/sony-t1.shtml
I don't have any experience with the T-1. It would not be a good choice for low-light situations where you would want a fast lens and need a higher ISO.
I also have an Olympus Stylus Epic (Mju II, I think, outside of North America.) I have the fixed lens version. It costs 8 times less than the T3, at least in North America. No, the lens is not as good. But you can get very good 8x10 enlargements from it. It also does not have manual overrides. It also has a critical, not fatal flaw: the default is flash. Since I rarely use flash, I have become somewhat adept at shutting this off everytime I turn the camera on, but this results in a certain lag (sort of like the lag on digital subcompact -- just joking, Bobtrips). On the other hand, offers a spot metre option, which I used quite a bit. The camera is not waterproof, but you can use it in light drizzle, and since it costs 8 times less than than the T3, you are more likely to take chances with it.