Unless you view playing a game as a job then PP is not a job.
It is just an added layer of politics on already existing game mechanics.
It adds a face and identity to otherwise faceless parts of space.
I think that is a good thing. Elite really needed that and PowerPlay delivers.
It needs a bit of refinement and tweaking, but I believe it is a great addition to the Elite universe and a great foundation to build upon.
You should join a power that offers rewards that you like. I joined A Lavigny Duval because she offers bonuses for bounty hunters and because I just happened to be very active in systems she rules. So I know these hunting grounds so to speak.
Currently the cycle completes on thursday if I am not mistaken. Take time to study the powerplay screens. There is a lot of info in there.
You do not have to pledge every cycle. You stay pledged until you
leave, or
betray your power.
If you leave the consequences are minor. If you betray, you will be hunted for a certain period of time. I personally like that and am almost seduced into betraying my power just to experience it

.
You asked if it was fun. I think it is, but it depends strongly upon the way you play. You can grind all the time or you can play it in a more playful, flexible manner. I do not dedicate 100% of my time to my Power. I do what comes to mind, but I take care to earn the merits I need in the mean time.