TrueOS is a rolling-release, desktop-oriented operating system built upon the FreeBSD-CURRENT branch. Its aim is to add desktop-usability, speed and grace to an elephant. It is more a FreeBSD tuning than a fork of it, anyway.
TrueOS is formerly known as PC-BSD; project changed its name, became rolling and mostly dropped pbi’s in late 2016.
I tried out FreeBSD just a few days ago as a desktop environment and concluded:
I am pretty sure (and I know) that FreeBSD is an impressive operating system for servers and I like some of its default security features and of course its filesystem. As a desktop operating system, however, it seems a bit crude and sluggish.
Thus, honestly, my expectations (as a debianized Penguin) were low also for its derivative.