At $400 it was the best deal you could make. It was the smallest scientific calculator ever made (in fact, it was the only pocket-sized scientific calculator). In the 70’s it was estimated that the majority of all computing power was tied up in these calculators. If you’ve ever used a slide ruler (if you’re old enough to even know what that is) then you know just what 10 digits of precision is in comparison.
My HP50g is still the best calculator available despite being several years old.
Braun was big on simplicity, but he completely overlooked the simplicity and power that is found in RPN (reverse polish notation).
There are other problems associated with digital signals. Many (if not most) fire departments refuse to use digital equipment (this includes the Boston fire department BTW) because digital devices have killed quite a number of firefighters.