Bought my 2006 4-door Focus ST (5 spd) in Jan, 2009. It had 6.5k mi. Now it has 44k trouble-free miles and continues to be dependable, economical, and fun. Just as tight and fun to drive now as it was 38k miles ago. 25mpg in town, 30-31mpg on highway at 70-80 mph. Has always been a great highway driver, and now with new Continental Extreme Contact DW tires, tracks like a toy slot car on the highway and just as pleasurable in town. Great combination of economy, value, reliability, and fun. Was hit from behind by Corolla while at stop light. Corolla's front end and hood was crumpled and couldn't tell Focus had been hit except for Corolla's paint on rear bumper.
Tight steering, nice handling, nice manual gear box, good gas mileage, engine provides great punch for a 4cyl, trouble-free, economical to operate and maintain, great highway driver, fun to drive.
No improvements necessary, considering the economy purchase price. For a more "refined" and/or "luxurious" feel and atmosphere I could have spent thousands more for a TSX or GTI, but having driven them as well I know the increase in driving satisfaction would have been insignificant.