I am old. I have been working with Unix for a long time. In fact, at the end of a recent job interview one of the participants said to me "It's interesting, you have more years of Unix experience than I have of life". Hmmm. Anyway, the point is, I think that the first "packaged" Linux distribution that I ever tried was Slackware Linux, sometime in the mid-'90s. I haven't had much to do with Slackware in quite a few years, though.
When I saw the release announcement for Slackware Linux 13.0, I happened to be working on MMS (my MultibootMiniServer), and I thought it might be interesting to try it on there. Then I read the release notes, and saw that it had a new release of Xfce, and that made the decision for me. So I downloaded and burned the DVD image, and booted it up.
Let me say that loud and clear at the start. Slackware Linux is not a distribution for beginners, or even casual users. Don't get me wrong, it is a very good and very solid distribution, but it is for big boys and girls who know what they are doing with Linux installation, setup and administration. There is no LiveCD, only the Installation DVD. There is no "Graphical Installation Process", only the (perfectly adequate) ASCII/text installation program. So if you go into this thinking you are going to do something like installing Ubuntu, Mandriva, or whatever your favorite desktop/graphical Linux distribution might be, you are likely to come out of it shell-shocked.
Experienced Linux administrators are likely to feel "right at home" with the installation process - I certainly did. Just about everything is there, presented clearly for your selection. It took me about an hour to get it installed on MMS. The only significant stumble was that Slackware uses the LILO bootloader, which I choose not to use, but even that wasn't a major problem for me because I have to keep the openSolaris GRUB as the bootloader anyway, so I just told it to skip the LILO installation, and added Slackware to the openSolaris GRUB configuration file manually.
There is a lot more to say about Slackware Linux, but I am still in the process of exploring it. For example, when the installation was complete and I had rebooted (via openSolaris GRUB), all I got was a plain old text "login: " prompt on the console. Wow. It didn't take long to figure out that I could login and use startx to get an Xfce desktop going; not long after that I figured out that I needed to set runlevel 4 to get the Graphical User Interface on startup. But there is a lot more to figure out. A lot more.