I recently returned from a trip to Italy, France, and the UK and I thought I'd report on my experience with using my US EMV credit cards on the trip. I brought along three EMV (chip and signature) cards, a Capital One Quicksilver, a Chase Amazon Visa, and a US Bank REI MasterCard. I also had the Capital One card set up with ApplePay on my iPhone.
At the Venice airport, I tried all three cards in the ATVO ticket machine for the bus to the Mestre airport and none of them worked.
At the Mestre train station, the Capital One card worked fine in the Trenitalia ticket machine.
None of the cards worked on the Milan metro ticket machines.
The Firenze Santa Maria Novella train station convienice store, the attendant couldn't get the Capital One card to work. This was the only case where a cashier wasn't able to cope with the card. There were other cases where the person was surprised by the terminal printing out a reciept for signature or didn't have a pen for me to sign, but they all worked.
None of the cards worked at the Paris Gare du Nord left luggage.
The Capital One card worked fine at the London Underground ticket machines to reload Oyster cards.
I used ApplePay at a couple places in the UK without a problem.
Oh yeah, I also got a Fidelity Investements ATM card for this trip after reading that it has no foreign transaction fees. I can report that from what I can tell, the ATM withdrawls I made were pretty much at the exchange rate that I looked up on the Xe app on my phone. Much better than the 3% + $5 charge from my local bank.
All in all, I think the EMV cards worked better than a traditional mag strip US credit card would have. I know the card companies are trying to require that all of the unattended kiosks take EMV cards with chip and signature validation, and it looks like it is moving in that direction. The larger organizations (Trenitalia, TfL) have made the changes and the smaller ones (Venice ATVO, Milan Metro) are behind. That's pretty typical for technology implementations.