I also haven't been able to "effectively use" the smart match operator. I've used it in some places to "just play around", but grep() or a List::Util function would have been just as good for the simple situations that I've used it in for experimentation.
I think that this thing is very complicated and is a "solution" in "search of a problem".
I haven't been able to figure out where this thing can be effectively used in ways that "normal" Perl is awkward or not sufficient. A big part of this is also whether or not the result of what it does is going to be "easily understandable".
