ITSM isn't about tools. it is a people issue first and a process issue second. Tools fix nothing. And they all work, near enough.
Good people can work with crap process and good process can work with crap tools. Good tools won't fix bad process and good process won't be adopted by unprepared unmotivated undeveloped unsuitable people.
once you understand the process transformation you need to make, only then do you understand what tool changes you need to make.
if you come at ITSM from a tools perspective you will have a bunch of unused/misused tools.
more at
http://www.itskeptic.org/node/77