We've used a Garmin Nuvi the last two trips with came with Europe maps. Even with updates, road construction and things happen. More than once Garmin got confused when it thought we drove off the road (because we were on a new road that didn't exist in Garmin). So a map is helpful, and just know what cities or towns or in the direction you are heading.
The other rule that really helped my husband and I from yelling at each other in a stressful "Garmin moment", is at round abouts, the driver is to continue circling quietly , until the Navigator (passenger) directs the driver to the correct exit out of the round about. We had multiple occurrences where the Garmin showed a 4 way intersection that was now a round about. You just need to look for the city names on the map to determine the direction you want to go.
And for fun before your trip, you can change the language to Italian (but not when in Italy)