I'm pretty sure it is. Never used it in the end as I couldn't get the drivers to install properly on my pc.
There are also some pretty easy manual steps to take - unlock the bootloader with one command from a pc, then flash ClockworkMod recovery to your phone with one more command (download the zip file to your pc first), then flash superuser to your phone using recovery.
I think what the tool does is just automate these 3 steps.
