I owe Arduino a lot though I never bought one (real or clone). I retired from commercial development in Java, saw these discussed, but looking at them I thought - that's just an Atmel chip on a board. Not quite true, but with a £10 programmer I got a range of DIP Atmel chips and found it was easy to program them with avr-gcc. It is a bit more complex, but not much, and very satisfying to know what everything is doing.<p>Ironically I do use the Arduino IDE with the esp8266 but I consider I will never fully know what those things are doing.