I returned to Australia about 4 weeks ago, having spent the 7 weeks prior to that travelling around Germany by train, staying usually about two to three days in each of the cities I visited. Before travelling and before buying any train tickets on line, I bought a Bahn Card that gave me about 25% off First Class fares; The Bahn Card cost about Euro50 for three months validity, after which it would automatically renew for 12 months, unless cancelled within the final four weeks of its validity. I found that the only way I could cancel the Bahn Card was to email DB, and to then hope for the best. Surprisingly, about a day later, I received their confirmation that the Bahn Card renewal had been cancelled.
My train travel in Germany was mostly fairly uneventful. When trains were delayed or cancelled, the DB App kept me informed, but the App seemed useless for actually making a new booking to replace a canelled train. I found the DB ReiseBureau in the stations to be excellent for assisting with new trains and seat reservations. I'm not German, but they all spoke good English, and were very helpful.
Some parts of the rail network were affected by flooding (in Bavaria), and trackwork near Leipzig. I had trouble getting from Dresden to Frankfurt Airport via Leipzig on my last day in Germany before flying home, but there were sufficient alternate routes and trains to allow me to get to the Airport a couple of hours late, but still with plenty of time before the flight.
I made one claim on the App for compensation for delayed trains, but I've heard nothing since. DB got the money for my tickets, and I eventually got to every place I had planned to be, so I'll call that a fair outcome. I'm not out of pocket from any delays.
I agree that on-train and on-platform announcements about delays etc are aimed at German speakers, but I could always find another passenger who could tell me what was happening. DB could improve this so much with simple technology.
The trains themselves were clean and mostly punctual. My seat reservations worked, even if I had to tell some people they were in my seat. My guess is they had no ticket and no reservation, but were seeing what they could get. In all cases, they moved without further ado.
Will I go back to Germany and travel by train in the future? Absolutely yes (next year)! I saved a small amount of money with the Bahn Card, but it is a money-saving device, and it is not aimed at recognising loyalty or frequent traveller status. YMMV, of course.