Actually no. German trains are often late, true, but outside of that its actually very nice. There are a lots of lines and lots of collections. The only time its a bad idea is if you have a real time constraints.
But the problem is: everybody doing a trip with a transfer has real-time constraints.
With Interrail, that is doable. You’ll have to mostly plan for overnight stays in large cities, but that’s what most Interrail users want to, anyways.
I try and avoid connecting trains. With each connection you only have about a 50:50 chance of success.