One of the best bits of Wipeout 2097 was getting just close enough to the wall to scrape against it sending sparks flying, but without losing speed. In Wipeout 3 scraping actually increased your speed which was a bit weird, but at least you could still do it.
In Wipeout Pulse it seems impossible to scrape against the walls and I think that's a change for the worse. But perhaps I'm just not good enough to get close enough to the wall to to barely touch it without losing speed.