I love driving this car. It is even more satisfying knowing that it's good on gas. I get better than rated mileage in this car. I haven't even modified it. This car is great for people who enjoy driving and who have needs beyond merely getting there. It's nice to have a spacious small car that still performs and isn't that expensive.
The shifter is perfect for both performance and comfort; I also love the suede racing-style seats, which are extremely stable and comfortable. The back seat is very comfortable for three adults. Despite being several inches shorter than my 2000 Ford Focus, the 2004 Si has a lot more interior room.
I wish the turn radius were tighter. The need for a sixth gear and a little bit more power have been solved in the 2006 Si coupe. The stock tires are poor -- better grip and tread life would be really nice. All-wheel drive would be extremely cool, too.