I am currently using the RC version of OpenSolaris (the new Ubuntu-like distribution of Solaris) on my laptop at work. It still needs some work to match usability of Ubuntu but the progress the Solaris guys have made is staggering. A year ago I couldn't install Solaris at all on my machine and today it runs quite well, although it was quite a challenge to get the network driver to run properly. The performance is pretty good, much better than e.g. Windows Vista and in some cases better than Linux.
If you want to find out about the new release a very balanced review has been written at Phoronix:
The RC2 image can be downloaded here. Final release is coming very soon!