Keep the topic please, Cpplikers away. I know from work, how troubly can be fixing one's buggy Cpp program. It is a crystalic hell on MCUs.

old gregg: On what series did you look? ST has a whole bunch of series of ARM micros. But it almost doesn't matter, which one will you pick first to learn them. STM32 micros are very well designed, and there are a lot similarities between all MCUs in all series. Unlike for example atmel or microchip, where each type of MCU is absolutely different with peripherals. That sucks like a bitch. On STM32 for example, when you have there Timer 1, you know for sure, that it is advanced control timer for motor control. For sure, yes, sometimes the micros differ, ADC converters are revised or used better, that pissful I2C periphral was changed on some series, and so... But there is a plenty of tidines, which really helps jumping between series and types. So if you learn one type from one serie, then you almost can use them all without a problem.
I would recommend to pick F0-DISCOVERY (STM32F051) which is easy to learn the basics and then maybe something from F1 series... Just what would you like the most. The point is, that with any discovery (or nucleo) board comes full featuring SWD debugger, which can be used easily to download or debug any other STM32 off the discovery board, without any limitations. You can use the discovery board itself as a programmer. Just open two jumpers and take the signals from a header.
That was the easy part. The harder part is, which toolchain to use. I am used to Keil MDK-ARM or IAR from work. They are both very expensive software, but I really like Keil. Keil also comes as free version limited by 32kBytes code side. That size might be just enought for small projects, but not for any serious work. You can download Keil uVision 5 from Keil's website and try that. Why to start on non-free tool like Keil? Because it simply works. You install that and everything works fine. Unlike some free tools, which always only adds some problems for beginners. In our country, we say "házet klacky pod nohy", which means something like "to throw branches under your legs".

Or, does anybody know about a free ARM toolchain which would compete with Keil uVision? I'd like to know, if such thing exists. I only use Keil/IAR at work or the 32K limited Keil at home, would be nice to have a comparable and free toolchain.

(I admit I didn't search for any, just want to hear your recommendation)
Thanx