Years ago, at Yeshivat D'var Yerushalayim, I took a class with a certain rabbi. He said that, "the Lubavitcher Rabbi stepped on so many toes that he had to be the 'real thing' or he was just a 'total fraud'". I tend to lean towards the latter.
What major impact on world history did the Lubavitcher Rebbe have. He never spoke at the UN, he wasn't looked up to by orthodox Jews outside his dynasty or by the misnaged Jews or by
most of the other Chasidic Jews.
One of Shlomo Carlebach's cousins took me to see other members of that family. One relative, a woman, told him that "Learning with Lubavitch isn't really learning", when he tried to push the Lubavitcher derech (path) on her.
At various Jewish gatherings, I keep hearing Jews from other orthodox groups complaining about Chabad. One person I corresponded with was from a group called Kayama (they help facilitate gets). He told me not to judge Judaism by a "semi-messianic cult", as he put it.
The problem is that believing in the coming of the messiah is one of Maimonides 13 "ikkarim" or principles of the faith.
So where does one draw the line?