I started using Ubuntu Linux when Mandriva, my current favored linux distribution, no longer installed on a new computer some 5 years ago. It was great then and I've never hesitated to recommend it for its ease of use and well maintained distribution of Linux. That changed with their 11.10 release which did away with the KDE desktop and forced everyone to use their new Unity interface apparently designed for use with notepads. Apparently, mouse desktop users are a thing of the past now. But forcing a linux user to use one interface is pretty much anti-linux philosophy. Even so, after the support cycle ended recently for the pre-11.10 versions, I was forced to upgrade into the kindergarden-level environment provided by Unity. I gave it a shot for a couple weeks and decided it was a piece of crap. At least for me. I think now it's designed for use by people who have no knowledge of computers or who are otherwise morons -- something I reluctantly decided, after long consideration, I was not. (No offense to legitimate and honest morons intended).
A saving grace provided after-market style by the linux community was that my favored KDE interface could be installed onto 11.10 and later Ubuntu versions with a software installation, thus allowing me to completely avoid Unity. Perhaps it works for some, and probably does, but it didn't work for me. I log in and 3 seconds later, I'm returned to the linux login screen. The 11.10 included the new Kmail2 program for handling email on my PC. Unfortunately, that didn't work and a net search found many complaints about it's failures and protests about why such a buggy program was included... nay, mandated, in a major Ubuntu release. Maybe Kmail is soon to go the way of the do-do bird, but until then, leave the dang thing alone, please.
Digging to the bottom of the Ubuntu barrel for solutions, I upgraded to 12.04 and the latest (greatest?) 12.10 in an effort to have KDE and Kmail work, but nothing did. So after a long and happy time with Ubuntu, I decided it was time to trash it as a desktop OS.
I've replaced it with Fedora Core, which Linux users will recognize as a long-standing distribution of Linux. Haven't quite figured it all out but the latest "17" release is installed, running KDE and the still working Kmail software (not Kmail2). It appears to be, so far, every bit as slick as Linux should be. Hopefully Fedora Core will continue to fly high well into the future.