A quick search takes you to the Cult Education Institute thread "Eckhart Tolle -- Comments From Someone who Knows Him."
The original post was by Wanderer77, who apparently knew him 25 or 30 years ago, before he became famous. She characterizes him from her point of view as:
An extremely, and I want to say, dangerously isolated individual, who has become worse,
Forum: "Cults," Sects, and "New Religious Movements"