I tried to use Ubuntu Mate for Raspberry Pi, but I had some problem. First, I could not get the check sum to match. I downloaded both torrent and direct img, but neither of them checked with the key on the web page. I installed it anyway... Second, Ubuntu Mate on Raspberry Pi was very slow. Perhaps it was something wrong with the iso or perhaps I am used to my laptop with 8 GB ram and Core i7 processor...
I downloaded Jessie lite, installed samba and ufw firewall and use Ubuntu Mate backup program. That will do for now.
Somebody should check the img on the web page against the check sum, perhaps the check sum on the page is wrong?