From the Dropline website:
Dropline GNOME is a version of the GNOME Desktop that has been tweaked for Slackware Linux systems. It is available in Slackware's standard .tgz package format, in addition to the usual source code. The current release is based off of the latest GNOME 2 distribution from the GNOME Project.
Slackware has long been renowned as one of the most secure and stable GNU/Linux system available, but its desktop has always left something to be desired. Dropline GNOME serves to address this while maintaining the core stability and simplicity of Slackware we all know and love. This is not simply a set of GNOME 2.6 packages; it has been tweaked and modified for a better appearance, cleaner interface, and a nicer integration with Slackware as a whole. Some of these differences are:
A complete set of i686-optimized packages
A convenient network-based installer and update system to easily keep your desktop up-to-date.
The latest release of FreeType combined with X.Org to display crisp, elegant fonts at any resolution on any type of display.
PAM integration, allowing configurable, increased functionality to non-root users (Example: changing the time or date).
FAM integration, allowing Nautilus to display an up-to-the-second accurate representation of your filesystem.
Library support for both ALSA (sound) and CUPS (printing). Niether is required, but the Dropline GNOME packages can take advantage of either.
A simplified, task-based menu system.
A default layout and theme setup designed to stay out of your way while remaining visually elegant.
What I like is:
1) Just looks "better"
2) DVD packages are installed so that you can watch DVDs
3) They have a nice support forum
4) Easy to upgrade
5) More frequently updated than Slackware alone.
6) PAM. I like it. Don't know what the security issues are.
Hope that helps,