OpenSolaris is ok. It's very pretty but, in my own opinion, they fail in the available apps in their repos. And they can be sort of difficult to understand for a new-comer.
My largest reason for this opinion is, the lack of graphics apps. and, when I tried to install an app to play DVDs... there are too many problems in the way of licensing, etc that get in the way.... 
Thank you, but I'm aware of these shortcomings. I know of a community repo that has the extra codecs and libs to play encrypted DVDs and whatnot (Fluendo is also working on porting its DVD player to OpenSolaris.)
I've used OpenSolaris before (several times actually) and have been tracking the latest development builds. Some things that look promising are Belenix, Korona, and possibly Nexenta.
I found out last night OpenSolaris does not like whatever happened to my Windows drive (it kept giving me a repeating error message about a "missing drive" or something, and couldn't install due to that drive being "not found.") Whatever messed up the Windows boot record sure did a good job of it.

And galjaman, thank you for the MEPIS recommendation. A friend over at the Raiden's Realm forums praised it as well. It's on my "to try" list.

I must confess Sabayon 5.1 is quite nice (using it right now.) Not perfect, but very good.
EDIT: I'm now on sidux.