Yaourt (Yet AnOther User Repository Tool) is a community-contributed wrapper for pacman.
Ranked in these QuestionsQuestion Ranking
Pro Equivalent to pacman
Yaourt commands and flags match pacman, so it is immediately obvious how to use it.
Pro Colored output
Pro Adds seamless access to the AUR
Pro Can be set up upgrade your system with no additional prompts
Pro You can adapt PKGBUILD to your needs during the (pre-)installation process
Pro Supports backups
More information here.
Con Does not perform clean builds
Environment variables may get carried over while building a package, preventing successful building.
Con Bad split packages support
Con Not maintained anymore
According to the Wiki page of Archlinux, Yaourt development is stalled.