We (parents and 9yo twins) took this trip last month.
Approx 600 km in 2,5 weeks.
It’s a great place to tour with decent bike paths and few roads with other traffic. Lots of interesting things to see along the route and easy to navigate, buy groceries and find places to sleep. Just remember that German stores are closed on Sundays.
Signs and bike path quality were a bit worse around Magdeburg, but really not a problem compared to bike paths elsewhere.
Train back from Dresden-Hamburg (via Berlin) in just 5 hours.
Can highly recommend 🙂
by hvasatan