I am running the latest version of ubuntu-touch/devel. However, I tried to get root access using the old default passwords ubuntu and phablet, but neither one is working anymore.
$ adb shell system-image-cli -i
current build number: 1
device name: mako
channel: ubuntu-touch/devel
alias: ubuntu-touch/vivid
last update: 2015-03-13 10:51:22
version version: 1
version ubuntu: 20141201
version device: 20141119
version custom: 20141201
