I've run FreeBSD on laptops, desktops and servers since 2.2.7. Laptops are not its strong suit. It works great for me as a desktop, but I've been tinkering with X desktop configurations for a long time, and don't mind doing some work to have a desktop that functions precisely the way I want it to. Also, it is not my only desktop. (/usr/ports/sysutils/synergy FTW!)
Servers and network appliances are where FreeBSD really shines. The ports tree can be updated independent from the base OS and the base OS can be updated independent of ports. No upgrading to a new OS just to get a security fix for your web server.
ZFS is brilliant. ~7 years of FreeBSD/ZFS and no issues.
PF makes every other firewall I've run (including every commercial option) look silly. PF is like the Python of firewalls: optimized for readability. Add in CARP and PFsync for easy fault tolerance.
The project is managed by a democratically elected core group. Like a real democracy, sometimes this means change happens slowly. But the deliberate approach to change is part of what makes FreeBSD great. It's stable, predictable, and reliable. It functions as a well-engineered, well-documented whole.
FreeBSD's biggest fault is how little attention it draws to itself. It is quietly brilliant. It just works. It doesn't try to do everything. It's just good, reliable infrastructure.