Mint has not beaten Ubuntu and the them is still grey (not cream as the OP claims). As of today, Mint is a bit over a hundred downloads per week from overtaking Ubuntu, but it has yet to beat it.
Mint Katya is awesome. I'm loving some of the Natty features, such as the floating sliders, the faster startup and shut down times and some of the new software choices. I'm really disliking the drop in stability though (ubuntu's fault, not Mint's), as well as the fact that some compiz features no longer work (or don't work properly - unless you hack them that is) - again Ubuntu's fault. I'm also really hating that they expanded mint search to almost every browser available for Linux (FF, Chromium and Opera), and make unisntalling the extension virtually impossible. To dissable it in FF you have to add another add-on, and to disable it in chromium, you have to uninstall chromium and side-load Chrome directly from google (and live with Chrome feeding data back to google). I have yet to find a way to disable mint search fro opera, which is a real shame.
Other than that, Mint is still awesome and quite easily the finest all around linux distribution there is. I have a strong suspicion that come fall, thinsg might not be quite as easy, as Mint tries to make gnome 3 work as gnome 2 has work traditionally, and Ubuntu makes further changes that will affect mint downstream.