I'm out of industry and back in school these days, focusing on autonomous robots to speak generally. One of the things I knew to expect was MATLAB, and I'm learning it as I thought I'd need to. But I don't want to make it my tool of choice in the long run. I won't give a technical review here (and I don't know enough yet to give a full review), but I'm generally a pro-open kind of person. And MATLAB is definitely propriety.
But it sure pwns the competition in the research world. (Update: I mean this in terms of apparent market share, not in terms of technical merit which again I feel too ignorant to comment on.)
The main alternative is SciPy. JScience and many other options for Java seem either unmaintained or too complicated. Hmm.