Math::MatrixReal has good documentation and a very good interface. It's intuitive to use and uses algorithms that generally have a low complexity.
Albeit I rate the module to five points in docs, interface, and ease of use, it's getting only four "overall" because, it just doesn't live up to the mightily complicated PDL in terms of speed. (Of course, the authors never claimed it did anywhere close to the same things.)
In conclusion, Math::MatrixReal is great if you're dealing with smallish matrices, but IMO won't cut the mustard in terms of memory efficiency and speed. It's pure-Perl after all.