The problem is I think Octave missed its window. 20 years ago when I was in grad school, everybody was using Matlab and a competitive open source version would have been a killer app. I looked into Octave at the time, but it was basically a toy at that point. I looked into it recently, and it really has come a long way, and even has an official GUI similar to Matlab's, but these days Matlab is kind of fading out and R is what everybody seems to be using.