Battery is great. I've actually been running this for about a year now. But I'm a hacker. Getting 13.04 to run when it was only Jan 2013 was a challenge. Also, installing Mavericks OSX on the dual boot partition fucked my ubuntu boot loader, so now I resort to booting with alt-option held down. Also, I had to rebuild gnome or something. I can't remember. It took me almost a day. Also, I don't have sound in Ubuntu, but that is a 13.04 problem since the HDMI output is on the same something something as the normal audio out.

Like I said, not for the beginner. Then again, what else am I supposed to use? Mac has by far the best hardware and OSX is a giant piece of crap for power users.

I would try mint linux, but I'm too afraid of being stuck without support.

I've thought of making a small side company that only sells rMBPs with dual boot ubuntu at a 200 dollar markup. I'd pay that, but maybe I'm not your normal computer user.