Kästner was born in 1899 and lived until his teen years in Dresden, so much of the interest for the modern reader is in how life was lived in pre-World War I Germany. There is plenty of detail about the street cars, horse carriages, food, and clothing of the time. His mother was a hairdresser and his father worked in a factory, so he was not especially privileged, but his parents sacrificed a great deal for the son's education when he proved to be a good student. They also took in boarders in their apartment, by coincidence all of them teachers, so young Kästner grew up with the goal of becoming a teacher himself.
I think my favorite chapter was the one where he described he and his mother's increasing love of wilderness hiking when he was an early teenager. They would take the train from Dresden out to the end of the line and hike all over Saxony, their trips advancing from afternoon excursions to day- and then week-long trips as they grew more experienced. They would hike all morning through Saxon hills, meadows, and valleys, and stop at a village pub for ice cream and beer in the mid-afternoon (yes, this is Germany, where a teen drinking a beer with his mom is not a big deal!).
There are also interesting stories about how his Uncle Oscar became a millionaire and what it meant for the family, how he learned that a hated teacher at his middle school wasn't such a bad guy after all, and how he discovered the solution to the bizarre mystery of the woman who hired his mother to do the hair styling for a wedding, only for the address she gave to prove to be an abandoned house, with none of the neighbors knowing the woman or having heard of an upcoming wedding.
Kästner's writing achieves a sort of beauty through simplicity, and he sometimes wanders off into later, sadder periods, only to write the German equivalent of "but that's neither here not there." A page or so when he laments the fate of Dresden in World War II, when the world-historical Baroque-era city center was reduced to rubble by Allied bombing campaigns, is especially moving. (Note he was anti-Nazi and was questioned by the Gestapo several times, though he was lucky enough never to have to flee or spend time in a concentration camp. But that's neither here nor there.)
Unfortunately, I don't believe this book has ever been translated into English (although Emil and the Detectives has been), so it's not really accessible to non-German readers. But for me, it was a lot of fun. This is the first German book I've read in I think three or four years, so this was a good way to get back into reading with a book that's not too difficult. Kästner was a great author with an interesting life, so if this ever did appear in an English edition I would not hesitate to recommend it to others.