I've used it off-and-on it always felt prickly, even with the excellent documentation.
For the big file system I use FreeBSD with ZFS, and we have a VMWare server to hold all the evil I am required to keep in my server room. The fact I have some damn government vendor who hasn't validated their product on anything past Windows Server 2003 is a little annoying.
It’s still a very niche market, though, so you have to stick to relatively well-tested technologies to avoid running into inconsistencies and issues.
I really like the lite-weight http server that comes with it. I've used it to complete a few internal only web sites for automating tasks around the office (importing data from other systems into our accounting system, firing off email confirmations to customers, etc.)
I have had very few issues with it and when I did it was generally me assuming I knew what I was doing because of my Linux experience. Once I learned to read the manual and look for subtle differences between BSD and GNU I found I was able to pick it all up pretty quick. Their manual pages are actually one of the best perks!