Many WP7 apps load so fast now that you don't even get to read the splash screen. In app scrolling on the few apps there were laggy works great now, though some WP7 apps still take time to resume. I've had a couple crash on me, but those were mostly games which weren't updated for WP8. Overall it's very impressive and I look forward to seeing how certain apps perform when made to work under WP8. There's a few apps I used on WP7 that aren't available and therefore not yet compatible, but again, its mostly games, and everything I really care about is available and works great.