trizen is a lightweight wrapper for the Arch User Repository and for pacman.
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Pro Easy to use
It's very intuitive and has a pacman-like syntax.
Pro Being written in Perl, trizen has an extra level of security over bash as well as performance and power benefits inherent to Perl
It is written in Perl in a functional-recurisive way, featuring full AUR dependencies support.
Being written in Perl (or any other language, except bash), it means that it can't execute/source (silently) the PKGBUILD to get information for a package, which guarantees an extra-level of security. Other benefits are the performance and power that comes with Perl.
The PKGBUILD is not executed before it is displayed to the user and optionally edited.
Pro AUR comments, search and upgrade support
It can display comments for AUR packages, search for AUR packages and check for AUR package updates.