I'm running 14.10 (and previous versions for about year) on an Ultrabook with a HiDPI screen that is actually a higher resolution than the MBP's Retina display.
I've set the scale to 1.38 for menu and titles bars (in the Screen Display settings) and everything looks great.
Chrome is a nightmare, there are some builds of Chromium that are better with HiDPI support, but Firefox works perfectly with the setting "layout.css.devPixelsPerPx" set to 1.8.
I've also set the text scaling factor to 1.58 (Using Unity Tweak Tool).
I'm completely happy with the results and when I use my Wife's MacBook Air I think there is something wrong with my eyes as the difference is really noticeable.
ten@vekony:~$ xdpyinfo | grep dimensions
dimensions: 3200x1800 pixels (846x476 millimeters)
I've set the scale to 1.38 for menu and titles bars (in the Screen Display settings) and everything looks great.
Chrome is a nightmare, there are some builds of Chromium that are better with HiDPI support, but Firefox works perfectly with the setting "layout.css.devPixelsPerPx" set to 1.8.
I've also set the text scaling factor to 1.58 (Using Unity Tweak Tool).
There is a good Arch Linux wiki page with some HiDPI tips - https://wiki.archlinux.org/index.php/HiDPI
I'm completely happy with the results and when I use my Wife's MacBook Air I think there is something wrong with my eyes as the difference is really noticeable.