I have never heard of him either.
He is a major "hero" with some people...unfortunately even Chuck Smith and Billy Graham praised him.
But, I don't think either of them understood that he denied core Christian doctrines like justification by faith alone, imputed righteousness, substitutionary atonement, and original sin.
I consider him to be a villain and not a hero. I can't see how he could be a Christian if he denied those doctrines, as they are core Christian teachings.
One of my pastor friends considered him to be a great hero, too, until he learned that the guy taught, basically, Pelagian theology. I guess people don't usually study the theology of these guys.
Finney would go into towns, and discredit their pastors by ridiculing them. Then he would preach to the townspeople, and many would supposedly accept Christianianity as a result of his persuasive techniques.
When he left town, the vast majority would forsake their alleged faith. However, the revival numbers looked good because a lot of false converts would profess faith.
Finney bragged about being able to convince anyone to come to faith within 20 minutes through his persuasive techniques. That is a clue to the issues with his theology. They were focused on persuasion and not the power of God. Another clue that there is a problem is that he focused on emotionalism and working the person into an emotional state until they responded.
Part of the techniques employed involved putting the person in a "witness chair" and interrogating him about his sins until he broke down and confessed Christ. I view it as some type of torture session. I imagine a lot of the people simply got tired and confessed even though they really didn't mean it.
This is all part of the "decisional regeneration" view of evangelizing. Bend the person's arm behind their back until they accept Jesus, and then you can cut another mark on the handle of your six-gun. Never mind discipling the guy afterwards, and integrating him into the community of believers you are a part of. This isn't real Christianity.
Here's a paper on Finney if anyone is interested:
http://www.sjsu.edu/people/jennifer.rycenga/courses/RelS191F12/s0/FinneyArticle.pdf