Most often when I see something about Joely-O, it comes across as if he's a bumbling idiot. He's just shiny-happy and smiley, and his theology is vapid and empty. The problem is thorough incompetence. And I can totally get that. Just listen to him dodge questions any 3rd-grader in Awana can handle easily, and you'll definitely think there's just no there there.
And that is where I think the danger lies. He may come across as a bumbling well-meaning doofus like Verbal Kint, but his Keyser Soze-esque heresy [no spoiler alert because that movie's old enough to vote, oh and Darth Vader is Luke's father] is every bit as deadly as that of any other prosperity non-gospel hawker like Benny Hinn, Joyce Meyer, Creflo Dollar, TD Jakes, Paula White, Robert Schuller, etc. He's not an innocent incompetent who's in over his head. He's yet another following the was of Balaam son of Beor, actively working for your destruction.
Want an example? Here you go. Listen to Osteen explain his theology, and Chris Rosebrough react appropriately. Just a warning - the Osteen update music is, uh, special. (On a side note, his update musics are great examples of polemical sarcasm. You learn so much about Mark Driscoll, Perry Noble, James MacDonald (2 songs!), Patricia King, William Tapley, or Rick Warren before you even get to the story.) It's about 20 minutes, but it's worth it if you think Osteen is just empty but harmless.
There is no such thing as empty teaching. If the teaching is devoid of God's truth, it will be filled with demonic lies. No exceptions, no matter how big of a smile it hides behind. Osteen's teaching is deadly. Keep yourself and anyone you love far, far away.