For some information and a chance to make an informed decision about this group here are some links.
http://www.jewsforjesus.org
http://www.jfjonline.org/about/statementoffaith.htm
http://www.jfjonline.org/about/history.htm
For instance I read that they were founded by a Jewish man, the majority of staff is Jewish and they use Jewish evangelism, not Christian evangelism which one may assume.