for medium-heavy data usage within europe you better select ROAMLINE, € 0.39/mb.
billing per only 1kb. best possible coverage, because roamline rate apply to almost every network per country, that KPN has a data agreement ofcourse.
www.roamline.com
this rate also apply while data roaming is US and Canada.
for light data usage (below 60mb per week) which is very little, choose ALdi talk "EU Internet-Paket 60" for € 4.99 which includes 60MB valid for 7 days.