Crouton is brilliant. It makes Chrome OS a truly viable proposition for developers.
FWIW, I've owned one of the Samsung ARM Chromebooks since the week it was released and I've been running crouton for a couple of months now and it works really, really, well. I still use the ChromeOS side for very simple browsing (the Aura window manager is nice if all you need is the web) but switch over to the ubuntu/X11 interface often to do development work.
1) Have you noticed any effect on battery life or boot time with the chroot environment in place? 2) Can I access Ubuntu CLI programs from the shell within ChromeOS or do I need to switch to the full Ubuntu window manager environment? 3) Any other disadvantages you can think of?