I'm running Vector 5.0 right now. Just installed it today. I put it on a Celeron 400, 64MB RAM, IceWM. Not too bad. Very usable. Firefox takes a few seconds for 1st boot, so does Konqueror. But overall quite usable. More RAM would help but its usable for all of you with old hardware.. So it should do a lot better on a better box. I put it on this meager box to see how it would behave. It will also run KDE but a little slow.
Stable like you would expect Slack to be. The install is a breeze too. Only problem I had was with X. Trying to get X the way I wanted it, I finally edited xorg.conf manually, but it comes with mcedit so that makes it easy. I installed all of it almost except for Open Office, I knew that would be molassis on this Celeron, it took about 2GB.
Comes with AbiWord, Mplayer, Gimp, GhostView, Firefox, KDE utilities, Gnumeric, all the stuff you need to operate with. Good job Vector.