Just thought I'd share my experiences of running 14.04 on my shiny new chromebook. I got this thing to replace my old Lenovo s205 which got a bit wet and hasn't dried out satisfactorily. Anyway since I was going to void the warranty by opening it up to fit a 128GB ssd I got one of the many nearly new 720s from ebay and a new ssd from amazon, total cost £220. For that fairly small amount of money I've got something that looks and behaves like an expensive ultrabook (if you squint a bit). The 1.4 celeron is an amazing little chip, subjectively it feels much quicker than the E450 in my lenovo, TBH it just clicking around the desktop and browsing the net feels as fast as my (old) i7 desktop though this is probably because the desktop doesn't have an ssd.
I'm not going to go into all the gory details, there are many howtos already out there. You can either install into a chroot inside chromeos (thought about this but figured there would be more breakage in the future going this way), dual boot (what I actually did), reflash the bios to completely remove chromeos (chance of bricking the laptop + power management is meant to be quite broken on the current version).
Here's very roughly what's involved...
Make a backup of chromeos.
Take the bottom off the laptop and swap out the ssd. (I found pushing in the base in towards the centre helped get it off without damaging any clips)
NB make sure you look very closely which way up the new ssd goes in, DON'T GO BY WHICH SIDE THE LABEL IS ON AS ONE HOWTO SUGGESTS! Look at the contacts on the connector, there should be 4 on the left hand side notch. It is possible to put it in upside down so be careful. I brought the exact same MyDigital ssd suggested by one howto and the label was on the opposite side from the one they had.
While the bottom is off, move the bios write protect screw over to the power enable screw (this lets you to make some changes to the bios and allows you to power it up without putting the bottom back on, be careful there isn't anything metallic on your desk! you can always put the bottom back on if you're a chicken)
Power the laptop back up and reinstall chromeos from the backup made earlier.
Put chromeos into developer mode.
Download and run the chrubuntu script to first automatically repartition the ssd and then install ubuntu (I understand you can change distro etc but I left it on the default ubuntu 14.04 64bit).
Once you're happy ubuntu is running OK it's time to make some bios changes so boot up is a little easier. By default you get a scary screen where you're steered towards putting the chromebook back into normal mode (which will wipe your install so you don't want to do it accidentally), you'd nornally press ctrl+d for chromeos or ctrl+l for linux. You can change this so developer mode can't be turned off and linux autoboots in 1 second. From the terminal in chromeos, switch to root and run set_gbb_flags.sh 0x489 then shutdown. (you can go back to the defaults by running set_gbb_flags.sh 0x0 but remember you need to remove that write protect screw before running this script)
Once shut down, move the bios write protect screw back into place, then reassemble and it's finished.
So what's bad:
Long boot time, (probably 30-40 seconds which is pretty bad)
Internal mic doesn't seem to work
Touchpad is a bit flaky (it's a clickpad and it doesn't deactivate the touch part so the curser tends to move around as you click other than this it's perfect)
Suspend seems to be broken.
No delete key (only backspace)
No caps lock (by default it maps to the super key SO IT'S REALLY HARD TO SHOUT ON THE INTERNET, maybe this is a good thing)
No function keys (like brightness, volume etc. It can be fixed but I'm not going to bother)
The keyboard doesn't have much travel in the keys, but maybe that's to be expected on a thin laptop like this.
I had to buy a usb3 gigabit lan adaptor as I sometimes need a cabled network connection.
When chromeos is in developer mode you can't use netflix
Speed, besides the slow boot it's amazing
Battery life, I've actually had over 7 hours use out of a charge
Bluetooth and wifi work perfectly
Price (there isn't anything even close to this thing)
Size and weight.
Plays the few simple games I've thrown at it on steam (Little street racers and world of goo, nothing heavy)
So if you're prepared to put up with the assorted annoyances it's a really, really nice little almost-ultrabook for peanuts.
I just wish someone like System76 would sell this as a proper product with all the rough edges smoothed off, even at double the cost of the chromebook version I'd still buy it.