I got my Raspberry Pi just a week ago (after 3 1/2 months of waiting). Downloaded the Debian image (I also tried the Arch one) threw it on a 8GB SD Card.
So… my impressions so far. It’s small. It’s quiet. Debian boots a little slow, Arch flies. Debian comes with LXDE pre-installed (but starts in console mode by default), the absolutely essential software (file manager, web browser etc.) and a couple of programming learning apps. Speed-wise the desktop experience is nothing horrible but it is what you would expect from an ARM device. It is powerful enough to serve its purpose i.e. provide a throw-away-cheap (but invaluable) learning tool.
It gets along pretty well with my LCD television using its HDMI port (I did have to disable overscan in Raspberry’s config file to get my TV’s native resolution). I wasn’t so lucky with movie playback when trying a couple of the conventional video players (a little slow, and some weird issues). Right now, from what I’ve read, your best bet is XBMC, and there is a tiny distro named OpenELEC, that provides a nice XBMC setup for that purpose. I think things will get better as more and more geeks get their hands on the Pi.
Now, from the Slackware side of things, right now there is an ARMedslack installable image available here, which I’m going to test on a second SD Card and possibly report back my experience. There is also a dedicated thread over at LinuxQuestions.org.
Right now my Raspberry Pi serves (among other things) as a headless anonymous FTP for Some Slack. To tell you the truth I had never setup an FTP server before, but vsftpd makes this really easy for you. You can access the server at someslack.myftp.org, where, you’ll find my Infinality and Humble Bundle stuff. Be warned: it’s not fast, due to limitations of my internet connection. If someone has any FTP related suggestions/tips, I’m always open to feedback :-)