I'm not a huge fan of Chromebooks myself, they seem limiting, but there are guides on how to put Ubuntu on a CB.
I'm already running a BIOS Arch on my C720, and am going to try UEFI w/ my new SSD for it. Google's own search can't seem to do a decent job of finding their own docs, but once I found where the write protect screw was, it all went fine, and Chrome OS was gone before I went to bed after I got it (by which I mean I stayed up into the wee hours of the morning, because I wasn't sleeping until I had a DE with fancy effects running

).
I paid more, just a bit before BB's deal (I am prepping XP machines, that were going to be thrown out, for a small stack of gift cards, though

). It's not great, but not bad either. I'm too clumsy to lug around a good modern laptop. Plus, new Thinkpad keyboards have gone to Hell, so I don't even want a recent used one.
The last-gen Acer C710 is much more versatile (upgradable RAM, RJ45, VGA, 2.5" SATA, and PCIe wireless), and has more keys; but the C720, once you tweak power settings a little, gets fantastic battery life, is substantially thinner, has bigger top row keys (with the shapeless chiclets, that's an issue), and no Windows/super/search key between lalt and lctrl.
Whether trying to mess with a Chromebook or not, though, just move on. That machine has had a nice long life...