I usually use it to visually unclutter code that would otherwise be an if with tiny blocks. It can be used in void context for something like

$i == 15 ?
    push @str, $_ :
    $j = $i += 1;
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or you can "chain" ternary operators by using another ternary as the false-branch of the previous:

my $res =
    $cmd eq "add" ? $x + $y :
    $cmd eq "sub" ? $x - $y :
    $cmd eq "mul" ? $x * $y :
    $cmd eq "div" ? $x / $y :
    undef;
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which would otherwise have to be a hideously ugly and thrice as repetitive thing like this:

my $res;
if   ($cmd eq "add") { $res = $x + $y }
elsif($cmd eq "sub") { $res = $x - $y }
elsif($cmd eq "mul") { $res = $x * $y }
elsif($cmd eq "div") { $res = $x / $y }
else                 { $res = undef }
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Makeshifts last the longest.