I also use MATLAB/Octave quite a bit for numerical algorithm prototyping, and mostly hate it. The language has a shallow learning curve, true, but for complex software it gets ugly very fast. It’s just not a well designed language, and if you have any CS background that becomes very limiting.
The thing that MATLAB brings to the table is the incredibly high quality numerics toolboxes. Octave gets a few of those but far from all of them, making it in my experience a poor runner up.
Whenever I have a choice I now go first to Julia. The language just makes me happy and the numeric infrastructure is almost complete enough.
Except for something like Simulink. When you need Simulink, there’s nothing else out there that’s a valid alternative.