With each subsequent release of Debian, installing this package gets more and more difficult. Having not been updated in over 6 years this distribution is badly crying out for some attention. As it stands, on certain kinds of machines you will need to patch the C source for some of the required ciphers, the test suite gobbles up entropy and can take forever to complete, you will need to install most of the optional dependencies if you even want it to complete, and you may still run into further quirks even if you get it installed successfully. If it weren't for upstream dependencies on this module I would advise against using it at all.
I have used this package for years and only recently have I had any problems. It does what it says on the tin and the documentation and samples make it easy to use but not to install. The main problem is whenever I upgrade Perl these days I get an error which is basically to do with the use of scalars and strict. This can be overcome by installing the Scalar::List::Utils package which you should download and install from source separately and keep so you can re-install it next time you upgrade Perl. The other problem was getting hold of the pari package which disappeared for a while so now I keep a copy of the distribution just in case. I mainly use it for encrypting emails using GnuPG keys without having to enter a password. GnuPG unfortunately lacks a simple interface for this since you can not pipe data in and out and use your keys to encrypt. If you could, it would virtually make all these types of modules redundant since a simple system call would do the job.
It's unmaintained with many outstanding bugs. The test suite often hangs. The module has no concept of key validity nor a web of trust. The only positive thing I can say about it is that it's a pure-perl module, but if you're stuck with needing a pure-perl solution for OpenPGP encryption or signing, you're screwed.
Crypt::OpenPGP provides a pure-Perl, well documented, easy to use interface to encryption services such as GPG. I can't currently give it a full five-star rating, because I still sometimes experience an odd bug when encrypting that I haven't been able to fully solve yet. :)
Still, if you are using to encrypt or decrypt with a PGP-like system from Perl, this module is my current primary recommendation.