As a newcomer, FreeBSD's new pkg tool is what sold me to the platform. I am too new school to to deal with Ports. I don't get much of a rush out of compiling my own binaries.
Does it offer something beyond OpenBSD's pkg tools?
A database backend which makes searching through packages, and occasionally being naughty and altering manifests, easi. It's fast as hell, like faster than apt, it lets you lock packages to a specific version, etc, so you can do things like have 2 or 3 packages built with special flags and still use the package management tools. It's fantastically clean too and well documented, as BSD software tends to be.