Meh.
Far to closed source now. Even when it was open though; I never grew a liking for it.
Fedora which is the open source end (Red Hat) of things, is very unstable and never secure. Which is where Cent OS originally grew from (they'll say Red Hat, I'll say Fedora).
I miss Mandrake Linux for what it originally started out as. Ubuntu reminds me of it in some ways, but thankfully so far has not lost sight in their original vision. Although I think Unity may have been their 1st mistake.
SuSe Linux is the distro that I've learned to love and hate. They seem to flip-flop on their vision and I never know truly what to expect from them. But I still follow them in their progress. It's a love and hate thing.
Mint Linux picks up were many believe Ubuntu should go and often I see Ubuntu Developers lurking within their project. It's not as stable as Ubuntu and often I feel as though it is missing something.
Debian is my all time favorite, but a lot of people shy away from this because it has a past history of not updating things. But that of course isn't so any more and Debian 7 is just around the corner. And if you're using Ubuntu, you're basically using alot that is built from Debian 7 with some mild impute from Debian 8 (not much, but it is there).
I like(d) Mandriva, they have allot of good stuff there, but it always falls short in some reason for me. Their control panel is by far the best one out there, and their ndiswrapper tool is nothing short of brilliant (it even removes alternative drivers). However, it still falls a bit short for me...
Fedora, I am not so sure what to say about. I liked their XFCE spin, but I never got around to love it.
SuSE is one distro I really like, but for some reason I always get hardware crash on that one. Also dependency hell was a nightmare. They have sorted it out a bit, but I still feel their package manager are a bit rough.
Mint was a distro I used for a year or so, but in the end I grew tired of it. I didn't like how they held back updates from Ubuntu, and I didn't like the direction it was taking. Also the whole debacle when you didn't enable root account, it basically locked you out of recovery mode.
Debian is meh, especially as a desktop. If I go that route, I much prefer Arch Linux, it is so fast and so easy to configure. And pacman is just beautiful, and rc.conf just makes it so easy to configure your system. I really wanted to install it on my desktop, but I never got the wireless to work on the install CD, so I am holding it back..