Personally the only problem I’ve had playing with a controller is that neither of the two vanilla interfaces can accommodate a party size of more than 7 including the Tav well and the mod to fix that isn’t compatible with the controller one. That’s pretty minor though, since it’s purely cosmetic and off to the side 🤷

Ending Concentration Spells answer:

Open the radial menu for the character that is concentrating so hard and navigate to that spell. When hovering over it, you’ll see options in the lower right corner of screen. It shows to hold ( Y ) down to cancel concentration.