first, some technical issues.
FreeBSD has the idea of a wheel group. in order to su to root, you must be in this group. it's just a level of protection around root, so that any random user can't try and guess the password and break in. most linux users get really confused when they try and su to root and it just doesn't work. it bit me when i switched over, so don't get confused by it.
FreeBSD uses a (surprise) BSD style init script setup, whereas most linux didtributions use a system V style. personally i prefer BSD, but it's just a matter of personal prefernce.
FreeBSD has a central repository that defines what is in the os. linux has many competing distributions that all try and define what is in the os, thus leading to some incompatability issues. on the other hand, linux is working to define some standards to fight this, and the multitude of distributions can work to encourage development through competition. it's an argument that can go either way, but i'm siding with BSD.
linux has one benevolent dictator, while FreeBSD has a bunch of committers and a core team that works together to decide on issues. there is no one person with veto power. i personally think the FreeBSD method will win out eventually, as linux will sooner or later scale past linus' ability to manage it.
linux is GPLed, FreeBSD is under a BSD style license. (but both systems include components that use the other kind of license) this is an old argument, and this is neither the time nor the place to have it again.
linux has a bunch of companies that are trying to make it into a competetive replacement for windows on the desktop. freebsd can use much of the fruits of these projects (gnome, kde, etc) but they are still rather linux centric. personally, i don't see the point in these kind of things, at least as far as my personal use goes. if i wanted windows i'd use windows. both FreeBSD and linux provide a similar unix like environment, which is what i'm looking for.
other than that, the major advantages i've seen in FreeBSD (if you ignore the stability and performance arguments, which are largely unsupported in recent days) are the build system, cvs tree, and the ports system. you've seen a bunch of info on those, and i don't feel like reiterating them, but they're the main reason i'm using it.