Hi.
This is my personal opinion:
Mandrake suffers from the same problem than Windows. Lots of nice GUI tools BUT, when these don't work, you are left with a lot of problems because you don't really know what these do. I also found the GUI tools are sometimes really buggy and do not work "as advertised".
Slackware is much "harder" than Mandrake because it does not have GUI tools, but, on the other hand, you HAVE TO learn the system and really know which file does what.
Once you grok how Slackware is organized, you actually use it and configure it much faster and with a lot more confidence, because there are no "bad surprises". The entire operating system works and is much more stable.
So, it's a question of "picking your poison": ease-of-use vs stability. Overall, I find the "Slackware way" to be better, but I totally understand why some people like Mandrake better.
Hope this helps...