I purchased my Scion new and plan on keeping this model for many years. It is fun to drive, the visibility is exceptionally good, my mileage is anywhere between 30 and 35 MPG depending on how many people are in the car or, what I am transporting to college. Compared to the 2008, which is larger and not as pretty am mine, I'll stick to my 2005 XB.
Visibility, comfort, position of dash gages, seat configuration, ease of parking. I could go on and on. The Xb is a fun car to own and drive.
The windows could stand a little more tinting, but they are ok. I really do not have any suggestions for improvements.