Or are there any effects putting production code into danger?

I wouldn't say so. perl5i, which aims to be production-code material, has full autobox support.

One advantage of the "everything is an object" paradigm is the fact that namespace pollution is totally avoided. This allows to have many utility functions for each particular data structure type, without the danger of overcrowding the main namespace.

In perl5i, for instance, you can now do:

say "  this is some title.  "->trim->title_case;

# This Is Some Title.
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or

my $paragraph = "Lorem Ipsum " x 90;

say $paragraph->wrap();
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There are many more methods specific for arrays, hashes, code references, etc. This wouldn't be practical without this paradigm, as it would quickly pile up into having either long and awkard function names to prevent collision (hi PHP!), or avoiding having them altogether.

At first, as many people here, I was skeptical as to the usefulness of it. After playing with this for a couple of days, I found that it can indeed be quite useful, and sometimes it also reads more naturally. YMMV.