The train is indeed the most comfortable means of transportation in Germany, but it's so unreliable nowadays that it's practically unusable if you need to get somewhere on a schedule.

Want to get to the airport 2 hours before your flight? Sorry, you have to plan in at least an extra hour, because there's a 40% chance your train will be severely delayed or canceled.

This unreliability drives people who need to get places on time to other modes of transportation. But if you don't mind being randomly delayed by an hour, the train is great. It's sad, and it didn't use to be this way.