It is nice until you start to write device drivers. I participated in porting it to an educational platform in Uni half a year ago, and the bit fiddling with MOD and DIV was really a pain.
This is no issue with my version of the OS since it is just an application and delegates the low-level details to my C++ code and Qt. And btw. there are some bit manipulation functions in the SYSTEM module, and it's easy to add even more.