Aside from being easy to work with when you don't have internet, the other upsides are the small footprint and light resource requirements, built in VMWare support, transparent and simple configuration and system initialization, and overall Just Works factor. The package repository has the things I generally want, and it's easy for me to set up my preferred development environment (xmonad, vim, firefox). As far as actually doing development, it's much like on any other *nix (xterm, vim, ruby, python, etc.).
If you're an OS geek, I don't see why you wouldn't want to have a look. I don't know if you'll prefer it over Gentoo, but you may be pleasantly surprised by the functionality and simplicity of the system. I find it a bit of a breath of fresh air when I get to it after time spent on Linux or OS X.
http://www.openbsd.org/cgi-bin/man.cgi
I moved from using Gentoo for 10 years to OpenBSD and have not looked back.
Edit; You gain quite a bit of time moving from Gentoo to OpenBSD because there is no requirement to compile or fix your operating system.
I use Xombrero (formerly called xxxterm) for browsing, or Chromium from packages if I'm working with anything on Google.
https://opensource.conformal.com/wiki/xombrero
I use Emacs as my editor and email client, and do pretty much everything else in a terminal.
http://s24.postimg.org/n94n4dred/fonts.png
I fetch freetype via CVS from xenocara tree:
cvs co xenocara/lib/freetype
Apply the subpixel patch (the Adobe CFF stuff is already default in -current):http://dpaste.com/hold/1438578/
And use the following `~/.config/fontconfig/fonts.conf`:
http://dpaste.com/hold/1438579/
You might also want to delete `/etc/fonts/conf.d/30-lucida-aliases.conf`.
Also, repeat the same after each snapshot upgrade, as the X sets will overwrite it every time, naturally. Don't forget to keep it updated as well, with `cvs up`.
I'd say if you're needing extensive font support, or do any really heavy graphics work, OpenBSD may not work well for you as a desktop. For me, the stock fonts on OpenBSD meet my needs.
That awesome looks um.. awesome. Never come across it before. I have an old netbook here that has a broken trackpad. I might be tempted to give it a go with that.
If you limit yourself to the package repository (about 10K packages) everything just works. Compiling things from source often doesn't, (not different than many linux distros). Tip: use the binary packages.
Also it can't run virtualbox or any other virtualization software, so sadly had to switch to Linux again. Soon...
Yes, I love both Operating Systems, I love that they are integrated and somewhat less retarded than Linux, I also like their community and development team and OpenBSD's focus on security and code-correctness.
But they are not yet "there" for Desktop use, many applications won't work or will be difficult to set up, and driver compatibility is way worse.
So maybe in a couple of years I'll switch to FreeBSD as a desktop, but for now Funtoo is still fun and somewhat usable.
Darwin's the successor to NeXTSTEP, which included a Mach microkernel and some BSD APIs and userland. When they developed OS X, Apple updated much of the userland using more recent FreeBSD versions as a base.
Even more confusingly, Apple has contributed some subsystems to open source that have made their way into FreeBSD (notably the compiler and libc++).
So Darwin's not a fork in the same way that OpenBSD is a fork of NetBSD.
You are really encouraged by the communtiy to use packages over the ports system, but you'll find everything you listed in both.
I hear pf firewall is awesome.