If your US bank card is visa or MasterCard (logo on front) it will work fine. There are fees - charged by US Bank - but it works. I have a us bank visa atm/debit card and have had no trouble in Sicily or elsewhere.
Call the phone number on the card before you go to tell them you are traveling- or else they may freeze the card on fraud suspicion.
I have on rare occasion run into an ATM where it won’t work. Could be a broken ATM or a network issue I don’t understand. Not a problem - just move to the next machine. This has been maybe 2-3 times over years of travel so not likely.
Use it for cash at ATMs. For purchases, it will work but you will pay less fees if you use cash or a no-fee credit card. I use a capital one master card for credit card purchases and the USBank card as an ATM card for cash.
Not everywhere accepts credit cards at all - be prepared to use cash at some places.