I have no personal experience with it directly, but the research I did goes both ways. While it is not malware per se, it is invasive, and apparently you have to give up some of your privacy to take advantage of it. Also if you do not use IE, it seems that you cannot use it, as it requires an activeX component. You should read all the privacy statements and all the legalese that goes with it to make sure that you are willing to give up whatever privacy they demand of you.
