After about 3 hours of gyming tonight, I have to say that this new system needs some work.
As I feared the other day, the coin payout structure is horrible. In 3 hours across 12 gyms, I collected 6 coins. 4 of those coins came from a single isolated gym that lasted 4 hours, the remaining 2 from separate 1 to 1.5 hour gyms. Everything else lasted 30 mins or less. People are going to figure out very quickly that getting coins this way is rough and not worth it at all. It's simply too much work for too little gain. If you're in a busy urban area, good fucking luck. Rural areas will work for now until the casuals get bored again and then you're screwed too.
Now for the matter of gym defense...there isn't any. Feed the first berry and get some decent CP back to your mon. Then half, then half again. And now you're adding almost nothing. And that's the extent of your "defense". At least before I could counter prestige and hold off an attacker or at least make it take longer for them. Now I'm just a minor nuisance, a small speed bump on an opponents guaranteed victory tour.
I also don't like the ever trickling down CP. Attacking did not need to be made even easier. You now only have 6 opponents max and they get weaker every round. I was able to smash through a Dragonite starting at 2600 5 times until he was off the gym with a single Lapras without having to heal. 5 battles and a gym turnover at the expense of 1 hyper potion.
The core of this update is good, Niantic just needs to balance it better. It's too in favor of attack, turnover is too high, and the coin payout structure doesn't reward enough upfront.
I think I'll sit the gym game out until the dust settles and the casuals get fed up and quit. I have 5000 coins socked away even after maxing my bag again. Never paid a dime for them either.
