Brief report from my first interactions with new system
I was about to head to bed and then saw on my phone that the gyms were opened. Raced out to my car and have now put mons in all 5 gyms in my town (2 Blissey, 1 TTar, 1 Snorlax, 1 Vap).
Three of the gyms were empty, so easy enough. First observation: When you put a mon in a gym it instantly loses CP. You have to immediately feed it a berry for it to reach its maximum cp.
The two other gyms both had exactly ONE Instinct mon. Both times I had to beat them five times. Each time they lost a little less than a fifth of their maximum health. One was a Gyarados that lost more than 400 cp per loss and the other was an Exeggutor that lost a little less than 400 cp per round.
The fights were pretty easy as the opponents quickly became weak.
I also noticed that the energy bar works differently. Now you seem to get set back everytime you are hit. Maybe Niantic wants us to dodge attacks or something. I'm sure someone else will very soon figure out exactly how this works.
A cool new feature is that you can see how many battles your mon have won when you enter a fight. Damn, my main Jolteon has killed a lot of Garys.
Gyms seem to work as less juicy pokestops. Even with the "Team bonus" I still only got three items from them. Also, actually spinning the gyms is a bit of a hassle compared to normal stops.
The graphic design of the new gyms is very cool indeed! No complaints there.