I looked on with interest in the mechanisms of Powerplay while the beta players were testing it. I remained unconvinced of it as a finished product, and so I chose not to participate when it went (prematurely) live over the weekend.
I'm remaining independent because it offers me nothing of interest to pledge to anyone. I get more out of the game just doing my own thing, and exploiting the PP regional passive bonuses.
I think Powerplay has the potential to be something pretty great, and integral to the modern Elite experience, but it all depends on whether Frontier are prepared to listen to the feedback.
For me, I'd have preferred it if they'd made the system of joining a Power more meaningful. As in, take the rank system that Major Factions have (Empire and Feds) and get rid of that.
Now, create the new ranks as part of Powerplay replacing this confusing and volatile rating nonsense. The rank is also something that doesn't have any decay mechanic. It remains at whatever level you achieve, and gets upgraded with your success and productivity over time, but can be subject to demotion should you underperform or fail in missions.
Make it so you progress within your power by being promoted in rank as you do more activities to help achieve its goals, and the longer you are a loyal and trusted part of it. Each rank level you achieve unlocks privileges and bonuses, such as better pay brackets, access to faction specific weapons, faction specific ships, Power related bonues... All that jazz.
Each Power rank, like the Elite ranks, are progressively harder to get, requiring accumulation of more activity credits per level. So casual players will achieve the lower ranks quickly enough, but have to play for the long term to get to the higher ranks. More regular players will get there sooner, just like the Elite or Anaconda grinders do right now, if that's how they choose to play.
However, whatever time you have, and put into the game, is your time, is static, activity based, and doesn't decay.