Only used the train proper, from Bastia and back, rather than the smaller trains or tramways. The…read morecross-island route we took is spectacular, runs reasonably frequently, and is very convenient to both cities. Staff at the station and on the train were friendly and helpful with our limited french, and overall the ride was comfortable even if the train did make some alarming sounds here and there.
Signage could be a little better, and when we left Calvi we were fortunate to have picked up our tickets in the morning because ten minutes before the scheduled departure time there was a line at the ticket booth and no sign of a ticket seller. Still, it seemed to get sorted.
During our stay we did experience both trains and buses leaving a couple of minutes before the scheduled departure time, too, so don't cut it too close!
