STM's documentation is a bit of a mess. I wouldn't recommend it for a beginner unless you're piggybacking off a development board that uses an STM32 core. This

STM's documentation is a bit of a mess. I wouldn't recommend it for a beginner unless you're piggybacking off a development board that uses an STM32 core. This way you can learn snippets of ARM code, but leverage an easier to use framework. Have a look at Atmel/Microchip's AVR documentation, it's worlds better. That plus avrlibc and a few tutorials and you're golden.