I ran across Linux MCE and the features seemed cool, but the one thing that got me, I know it's silly but I liked it, was that while the system was idle it displayed picture on my TV from flickr.
This is honestly my #1 favorite feature of the whole program. Those Flickr photos look so good on a 42" at 1080i/p.
But as for the versioning, 1.0 is very stable, but utmost requires a clean install of Ubuntu (NOT Kubuntu). 1.1 is currently in the beta stage (beta 2 to be exact), which means it is not completely stable, but it's not a final release. (see http://en.wikipedia.org/wiki/Software_release_cycle#Beta
If you want a stable version of LinuxMCE, please install 1.0. It runs on Ubuntu (Gnome), not Kubuntu (KDE 3.5), which has a few draw-backs, one of which is that it cannot support two sessions of X running the nvidia driver, so one has to use the vesa driver and the other has to use the nvidia driver. One of the main problems with 1.0 is that it heavily modifies your system configration, which is why it is recommended to install it on a blackbox.
I might end up installing 1.0 if this 10th and final install of 1.1B2 fails. I will find out when I get home early this week.