Just got back from a long vacation around Europe using only my arrival+ card.
Transactions that showed up redeemable:
-All Trains/Underground/Metros in London, Paris, Germany, Switzerland, Italy
-Ticket to summit of Mt. Titlis in Switzerland (shows as 'ENGELBERG ZB'), purchased at ticket office in Engelberg
Transactions that were not redeemable automatically:
-St Pauls Cathedral
-Eiffel Tower
-Windsor Castle
Calling up Barclay they seemed to have no problem manually using points for those 3 purchases.
Other than those 3 transactions, I had zero problems using the card through Europe. Chip+PIN worked as expected when needed