Big difference to other MCUs is that the propeller has very little hardware add-ons. No I2C, no serial interface, no AD and so on ... oh .. not to forget NO INTERRUPTS. Only a video generator per COG and 2 counters per COG (COG is the name of a core). On the first glance this does not sound very good!
But that's exactly what the 8 COGs are meant for. Instead of adding hardware here and there and offering thousands of different types of microcontrollers for every possibly useful combination, the propeller is designed to do all that in software or get support by external chips that do things much better than the internal circuits.
SPIN supports modular software development by so called Objects. And Parallax supports the developers by offering a internet platform for Object Exchange. So, if you need a chip with 8 serial ports ... pick an object that implements 4 serial prots per COG, use it in 2 COGs and there you are.
I did PIC programming and AVR programming before, but the propeller is so easy to use and you get results much faster than with other controllers. Mainly because the Objects can be used without changes in most cases. Interrupt driven controller software most times needs to be adapted to fit in the own environment.
The software is a FREE download on Parallax's web site. You will need to purchase a programmer, such as the PROP PLUG, for a modest price.
That could be missunderstood. You don't have to buy a PROP PLUG. I'm still running my propeller on a breadboard with a non Parallax USB to serial converter. In their documents you can also find a serial interface which only needs some resistors & transistor.
For a start with the propeller you only need:
1. the propeller
2. a interface (serial or USB to serial)
THAT'S IT! Very inexpensive.
Of course some Objects will not run at that low speed.
A 5 MHz crystal to get the full 80MHz internal speed generated with PLL. (full speed means the speed given in the spec as max. frequency ;o)
A min. 32kByte serial EEPROM to store one program.
Ah ... EEPROM ... another difference to other microcontrollers. The propeller does not have any internal non-volatile memory to store programs on, like FLASH or internal EEPROM. It's booting from external EEPROM -or FRAM- into it's internal RAM. I already damaged AVRs just by programming to often, which I think is very usual when developing programs. This won't happen with the propeller! EEPROM gone? Well .. attach the next one.