It's actually the opposite: go inside a city, boom, no mobile data.

Luckily, things have improved and network cells aren't overloaded all the time.

In the countryside, all networks are hit and miss.

I am out of the city.(close to Dutch border) O2 is best here. Even better than Telekom.

I do understand that its not universal.

But O2 is a pretty good alternative. Especially if I consider than I pay one third of the price that a similar contract would cost me with Telekom.