I think you are expecting too much out of a
resistive touchscreen. Being a long time PDA/smartphone use and now an iPhone user I appreciate the difference. For day to day use that involves scrolling and a virtual keyboard a
capactive touchscreen is worlds better. Its just easier to use since you don't need to apply much force.
That said, I think on a device like the sony you can get away with a restive type screen. This is not something that people are going to be typing out emails on or trying to navigate web pages. The user input is basically limited to selecting menu items, double tapping words and occasional keyboard use. Admittedly I don't see the stylus as being an effective way to take notes in the real world.
However, while we are on the topic, why hasn't sony gone the capacitive route? I suspect it has a lot to do with cost. I'm also thinking that a glass capacitive panel would eliminate much of the clarity issues we see on the existing touch screen models.