Three things about the MSP430:
* it's a very clean/beautiful/regular architecture, so people who want to do low-level stuff will find it a very good place to start
* Matasano made a security CTF that is based on hacking software on a MSP430 using a debugger and a disassembler, which is a really fun way to learn about the MSP430. It may be one of the best games you have ever played: https://microcorruption.com/
* TI sells their MSP430 dev boards, called Launchpad, really cheap on their website - $9.99 for the basic board. They will even 2-day ship it worldwide for free.