This is nothing short of amazing. We can of course ramble about how this is unsuitable for a modern multitasking multi-user multi-use OS, but for an OS-as-a-tool, it's amazing. The simplicity of almost all characteristics makes programming and hacks a lot more accessible. Nothing really encumbers you from getting a job done, even if your solution is a hack.

The sort of unbridled, interactive access is very reminiscent of a Lisp machine. Most things are dynamic, almost everything is changeable. The Lisp machine likewise wasn't a good multi-* OS, but it is probably the best OS-as-a-tool ever made.