This is true. DB trains get me from one point to another point, and in my experience, are usually not more than a few hours delayed end-to-end.
Remember that if your train is delayed more than a certain amount (30 minutes?) you have the legal right to ignore the routing on your ticket and take any train you want, that leads towards the destination on your ticket. Consider it an adventure. The app can suggest alternative routes in real-time, and you can also ask at the info desk at any station that has one.
Huge number of people use DB for regional transport for commute. They get affected by 10 mins delay since connections are missed
Nitpick: Unless it changed, you cannot upgrade from regional to interregional vehicles. You can upgrade from IC to ICE, though, and in general, the free choice of vehicle on your route is very useful.