I never thought I'd write an online review, but I simply had to come back and confirm that this car is indeed every bit as good as people say. I needed to get a new car and heavily researched the Mazda3 in addition to the Honda Civic Si, Honda Accord Coupe, Mitsubishi Lancer, Subaru Impreza WRX and BMW 328. As you can tell, price was not so much of a issue for me as getting a car I really liked. I was worried that the Mazda3 was underpowered and too "economy" (i.e. cheap and mundane) for my tastes, but after driving all of the cars mentioned above I was left with little doubts. Without exaggeration, this car drives and handles like a BMW. I could not be happier with the purchase.
The interior build quality far surpasses all my other choices with the exception of the Accord and BMW. I can't believe I'm driving a sub $20K car. Also, I would highly recommend the manual transmission. The gearbox is so wonderfully refined that it feels German and the short-shifter is heaven.
Honestly, I have a hard time coming up with anything. I've read about people having issue with the engine noise, and I don't understand why. Hearing this peppy 4-banger rev up and scream at you is thrilling. If you want silence then get a Cadillac :)