I use prepaid zero every time I am in Europe for the convenience of being able to use one sim card through all countries
Coverage over all (most) European countries.
Clear set-up instructions.
Overnight responses to any queries.
Improvements or suggestions
The service has improved over the years.
5 years ago in Rome the sim card took several hours to connect which was a bit frustrating but now it is minutes.
Cards arrive at home in about 2 weeks now