I have found the AC to work quite well, so far. It does take a little time to cool down, if left out in the sun all afternoon. I leave my AC going all the time when I'm out running around. The impact on the battery seems minimal. If I'm only going to be a couple minutes, I just leave it running and lock the doors. If I'm going to be longer, I turn it off and lock it and then use the phone app to turn the AC on while I'm inside.
I've only had the car three months, so I'm not sure how the heat it going to affect the battery. It spent the first two summers in Georgia, and shows 87% for the battery health. The yearly battery checked showed everything to be fine. I've got three full summers to see if the heat degrades the battery pack enough to get a warranty replacement. If not, maybe I'll be able to buy a higher capacity pack to go in it. Guess I'll have to wait and see...