Let me start by saying I have never personally used Mandrake. I have never installed it on one of my machines or had the chance to really look at what it can do or what it is made up of. So take this for what it's worth
I do however spend some time helping people out in IRC with linux related issues that I am knowledgable about. It is through this assisting that my utter dislike for Mandrake stems.
I have two major reasons for disliking Mandrake. The first is the fact that it crams an exceptional amout of crap upon a user. Like RedHat, Mandrake is designed to be a user-friendly distro that is good for noobs. I beleive that the only real grounds for this statement lie in the install process. But once you have it installed it seems to force crappy GUI tools on the user, trying to make itself "windows-like". Ok, for crying out loud, Linux IS NOT FRICKING Windows! And with any luck it never will be. Trying to cover up the way Linux was designed to operate with user-friendly gui's and other assorted short-cuts is not doing anyone any favors. It merely hinders a person's learning of the true way Linux operates.
But even more so that that, what really pisses me off to no end is everytime I'm assisting someone who uses Mandrake, it inevitably turns out that they DO NOT have gcc installed. Linux and no gcc? Heck, no compiler of any sorts!!! That is flat out ridiculous. Now I know you're saying "but not everyone programs so why would they need it?". Well, in Linux, the way you install programs is by getting the source code, compiling it, and away you go. Now sure there are such things as rpm's out there, but we all know those aren't the most reliable things out there. I don't care what kind of install it is, desktop, laptop, server, etc, every linux install should have a compiler installed with it. It's not like it takes up that much room, and it's usefullness far outways any negative factors that may exist.
So I say damn Mandrake to the pits of hell! If you want a user friendly Linux to learn with get RedHat. It might still be as convoluted as mandrke, but at least you will have gcc installed and ready to go when you need it.