Yep. I have tried various versions of Knoppix, Redhat, Mandrake, Fedora Core 1, Mandrake Move, etc. I also have LindowsOS downloaded, may try that in a few days.
Do I like it? Haha, I could rant for hours. To be polite, no.
First, by the nature of their design, Knoppix, Mandrake Move, and other live CDs (entire operating system runs off the CD) are going to be slow. They have to load the entire operating system off of a CD, which takes much longer to read from than a hard drive. And then it has to also decompress everything it has read. It took longer than five minutes for Knoppix to start on my pretty fast desktop computer. I do understand the point of live CDs is for testing, but it seems to be make a poor impression by being so slow and unwieldy.
There are many things I find interesting about Linux, unique technologies mostly. But I find the overall experience quite... unsettling. I'm a computer science student, so I spend a lot of time programming, studying algorithms, reading code. When I use my computer for leisure, I expect everything to work, without any twiddling or hassles. In my humble experience, things very rarely work out that way with any version of the various Linux distributions (hardcore Linux fans will get upset if you refer to the entire operating system as Linux). Simple things like installing Flash for your browser can quickly become a nightmare, unfortunately. Check out this article about one person's attempt at installing Fedora:
http://www.osnews.com/story.php?news_id=5111 .
I also have a lot of thoughts about centralized repositories of software for installation, and the elitist attitude that sometimes prevails within the Linux community... but for everyone else's sake, I'll stop ranting (sorry!).
Anyway, I'm not trying to discourage you. If you find a distribution you are happy with (and there are many to choose from), you may save quite a bit of money compared to purchasing Windows, or a Macintosh.