In my opinion, there are some serious flaws with all of them. I've installed Mandrake 8.1 on two different desktop machines and a laptop, and each one has some sort of weird problem with aliasing /dev/cdrom to the correct device. (And I'm talking standard ATAPI hardware here, all IDE!) I knew how to fix that problem with the older 2.2 kernels, but the new "devfs" crap, which isn't documented well at all, has changed the way everything works and I can't manually fix the aliasing problem. I have to manually configure all of my programs to point to the exact disk controller that my cdrom drive resides on because the link is broken. Do you think a newbie would be knowledgeable enough to fix a problem like that?
Then there are just a huge list of annoyances that, quite frankly, would NEVER exist on Windows.
I'll give you another example. I wanted to figure out one day why my Xmms was not synchronizing its graphic equalizer display properly with the music that was coming through my sound card. After playing with it for a while, I found a bunch of other problems. For example, if I held the left mouse button down (such as when I'm dragging a window around on my screen) for more than about 5 seconds, sound output stops completely! When I let the mouse button up again, it will resume. Very quirky behavior. I decided that it had to do with the way xmms sends the sound signal through this program called "artsd", or alternatively on some other systems, "esd". I didn't know what this program did at the time, so I typed "man artsd" to try to figure out what it did. The response I got was "no manual entry for artsd". At that point, I gave up. It just wasn't worth fixing. I don't want to go on a wild goose chase just to find a manual entry to some program that I didn't even want to use in the first place.
There are COUNTLESS problems like this that have cropped up on my systems. I don't have the space to name them all here. Things that are supposed to work don't. SMB access through Konqueror, for instance, doesn't work as advertised. Xemacs refuses to change font faces or sizes, bombing out with some error like "wrong type argument: number-char-or-marker-p, nil". The SAME version of Xemacs running with the SAME .emacs file works perfectly on my Solaris box and a FreeBSD box.
If you really want to learn and use a Unix, I'd seriously consider one of the *BSD variants, like FreeBSD or OpenBSD. In my opinion, once you get familiar with the command line utilities and startup scripts, you'll never turn back to the buggy GUI interfaces that seem to be the only allure of Linux. With the single exception, perhaps, of Java support, which is quite lacking on *BSDs.