In pocket if you hit the unlock button of the P3, then slap your whole forefinger or thumb along the middle of the P3's screen (do it length-wise) once....then again....it will have paused the song that is playing. It only takes a few times of practice then you can get it well over 90% of the time on the first try. It's not that hard to manage at all. If you are decent at manipulating devices blindly it will be easy to pick up.
Going forward or reverse in your playlist, pause/play, is all easy in pocket or while holding in hand driving. It's actually easier to screw up which volume button you hit I think...since the speaker seems like another button when you are not looking and not thinking about it. What an idiotic design and placement for a speaker...
Favorite song right now - "Dear Life" by Anthony Hamilton. Recommend you try it out.