There was a brief look at the new, big-button interface for the NGP at Sony's unveiling. It combines your trophy achievements and social gaming activities in one and provides access to the store, a browser and games.
Using the touchscreen, its a lot more iPad then it is PSP, which is probably a good thing. Getting around will be quicker and hopefully the ability to theme and skin the console will lead to lots of distinct styles.
I think that pausing a game and nipping off to do some socialising and then going right back in won't be a problem and hope the browser is a more modern affair than the wimpy PSP experience.