Hahahahaha, zoom. Since I installed the 13.04 version of ubuntu on my MBP retina, I get the pleasure of cruising the web at 200%. Half the sites out there break.
I do use Chrome's. It does work way better than FF, but you'd be surprised at how much text out there is loaded with third party JS or flash and doesn't "grow" with the the zoom.
You might wanna try Opera 12. It's going the way of the dodo, but it has always had the best zoom of all browsers. In my experience there are only some few video applets that don't zoom properly because they render in exact pixels.
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.