Ada is fairly easy to use once you know it. It has a few quirks and many nice features. It just takes a bit more time to learn, because its way more strongly typed than most other languages. IMHO, its main advantage is not safety, though, but readability and long-term maintainability. You can take a 30 year old Ada program and compile it with the latest version of GNAT.
Anyway, please don't compare languages like Ada and Python. That's like comparing Forth and Smalltalk or apples with oranges. They have different purposes. Ada compiles to executables that run around as fast as C and C++, and like those languages it's not very suitable for rapid lego-brick type programming. For gluing together existing libraries, languages like Python are awesome but you wouldn't want to write an Operating System in Python.
My point is that "fast as C" is meaningless. You can write quite abstract/unoptimized C. And you can write Python code with a few Cython-specific annotations that rival "regular" C code.
Anyway, please don't compare languages like Ada and Python. That's like comparing Forth and Smalltalk or apples with oranges. They have different purposes. Ada compiles to executables that run around as fast as C and C++, and like those languages it's not very suitable for rapid lego-brick type programming. For gluing together existing libraries, languages like Python are awesome but you wouldn't want to write an Operating System in Python.