It's your choice really
There's really no rocket science involved for slackware or any distro I guess - all that's required is patience and resolve.
If you hit a problem you'll find most answers on here and you can always go back to mandrake.
The latest version of dropline gnome from
www.dropline.net in my opinion looks great and behave's well for a desktop and swaret, again downloadable, is great for keeping your system up to date.
If you go for it you'll probably find you end up configuring/doing most things via the command line which becomes an incredibly intuitive and fast way to do things.
The choice is yours