I have a 2004 Mazda with the 2.0L. I've been more than happy with it. I decided to go with the 2.0L because I felt it was more than adequate for what I needed, and besides, during the test drive of both the 2.0L and 2.3L models, I did not notice an appreciable difference (not worth the hit in fuel economy and cost for the upgraded model). However, if I could afford it I certainly wouldn't say no to an engine spitting out 263 horses!
I agree with DrinkDuff's analysis of the vehicle. The handling is the best aspect of the car. With the 5 speed, I safely average 38-40 mpg on the highway, and somewhere between 24-26 mpg in town. Mind you, I drive fairly sedately and I don't push it too hard very often.
The fit and finish is a bit rough, but I certainly saw much worse (Pontiac Sunfire - the engine/tranny seemed fine, didn't handle that well, but body panel gaps and interior fit and finish was embarrasing) when I was looking at other vehicles before I settled on the 3. The glove box doesn't latch very snuggly and as a consequence rattles over rough roads. There are a few squeaks and rattles elsewhere, but considering how terrible the roads in Saskatchewan are, the car seems to be holding up pretty well. DrinkDuff is right in that the paint has a orange peel look to it. It isn't the worst I have seen (I've seen some terrible examples even on very expensive vehicles), but it is noticeable in direct sunlight.
Reliability wise, it hasn't caused me any major problems. The most serious thing so far was the rear motor mount deciding to ingest some pebbles and dirt, which caused a horrible racket. According to the dealer this is something they have seen with the 3, but I don't know if this is an issue they have addressed in the new models. I'm trying to get the dealer to replace the motor mount as they have been known to fail prematurely, I'm sure especially when they get dirt and abrasives stuck in them.
Overall, I'd certainly recommend it, but I wouldn't hesitate to see what is out there right now from some of the other car companies. I wasn't certainly set on Mazda, but after driving the vehicle, I sure was. If I was to make the decision again with the choices I had at the time, I certainly would buy the 3 again.
Cheers,
Mike