I've had my 2004 Focus ZX3 for a little over a year now and so far no problems. I've heard Ford had fixed all the problems in the previous model year Foci into the 2004 models and it's pretty obvious. The 2.3L PZEV engine is very torquey at low RPM ranges, around 3,000 rpms, which is practically everyday RPM ranges. Very smooth ride, nice interior, and beautiful styling. Fuel economy isn't as great for a car this size, however. I calculated an average 26 mpg city/highway driving, which is what you'd expect from a larger vehicle like an SUV. But the 2004 Focus is an overall great car to drive that's actually more reliable than the previous model year Foci.
2.3L PZEV engine is torquey and has quiet decent power, nice sound system, nice interior with convenient controls, nice exterior styling.
Could use a bit more power coming from a 2.3L engine.