Seconded. My use case might be running my own Ruby scripts faster, but they don't need to run any faster so it's not worth the trouble of setting up a development environment, especially one that requires a compilation step.

It would be a totally different thing if it could run Rails, which is one of the things I do in my job. The speedup would probably justify using it, especially when running tests on my laptop. My customers are perfectly happy with the performance of Rails on their servers. Same with the ones using Python with Django.