As with any new models, the first two years will be rocky. Because it's a new model, there's bound to be some issues with it. Chances are, it will be fairly minor because Mazda/Ford have had a chance to massage issues with the Mazda 6 and US-based Focus Duratecs between (2003 and 2004). I haven't heard much of negative rants with the new 3 yet.
I wouldn't be frightened off by any major repairs, provided you're doing them as part of preventative maintenance. It all comes down to that. Eventually, machines break down. However, the frequency depends on how much you take care of them.
Given the resale value, I'd keep the car as long as you can. Parts will probably be abundant as time progresses (ever note how many Contours/Mystiques are on the road now?). When you need to do a major repair, that's when I'd start debating Roxy's future.
