Impatient Perl ($free, 2004, self-published, "GNU Free Documentation License, Version 1.2 or....") clearly identifies its target audience: "... people who either want to learn perl or are already programming in perl and just do not have the patience to scrounge for information to learn and use perl." But its approach sometimes suffers from catering to the impatient -- in this case, by presenting material with misleading information.

For example, London offers the following (at 1.4) as "Your First Perl Script, EVER"

Create a file called hello.pl using your favorite text editor. Type in the following:

#!/usr/bin/env perl
use warnings;
use strict; # comment

use Data::Dumper;

print "Hello World \n";
[download]

and then proceeds to assert:

1.5 Default Script Header
....

#!/usr/bin/env perl
use warnings;
use strict;
use Data::Dumper;
[download]

Granted that where I've placed the ellipsis, London states that it's an "assumed" default block header for the book, but, IMO, including the unused D::D in the "first script" and the potentially misleading title of 1.5, are just two of the defects which detract from its value as an authoritative primer. (It may well serve better in its second stated purpose: "... use as a handy desk reference for some of the more common perl related questions.")

Update:

1. Maybe the $Not_Free version has been updated from the html version? I didn't spend the money to find out.
2. The link in the OP fails to find "Impatient Perl" but references a possibly similar text, in French, PERL POUR L'IMPATIENT 2E EDIT (ISBN: 2914010729 / 2-914010-72-9 ) by a different author, "Desreux S."