I have used this for a while, without any problems.
There are options listed on the left hand plane, which can be ticked or unticked according to your preferences. Also there are options to 'save' certain cookies(eg: remembering ones email addy) so as not remove those cookies from sites that you visit regularly.
Its hit and miss with all your opinions, I have ran it twice and it has found loads to remove, I set a restore point the first time I ran it. Incase it went pear shaped. But all seems fine.
Still not sure; guess I could waste a few hours on an install if it goes wrong but I doubt it from what most are saying. I don't allow passwords to be saved etc, and I always empty cookies and what not so if it deletes them before I manually do then fine.