Joseph Webb stated that passion is more important than eloquence in his book Preaching Without Notes. I heard a preacher who is pretty effective with a full manuscript. A few weeks ago he preached a sermon that moved many people. However, today he preached a sermon completely without notes. He did have more passion than normal. He also moved around and had better eye contact with the people. But, his sermon had some major structural problems.
First he used illustrations that did not fit in with his point. Second, he had more than one major text to guide the sermon. It seemed as though he was preaching two sermons as the two major texts fought with each other. Finally, as the texts seemed to conflict with one another so did the major point(s).
Webb would say that we should blame this on a lack of preparation not on preaching without notes. I say that a good sermon is always more important than whether you use notes or not. All things being equal, without notes is probably better, but if one has to choose between a well crafted sermon that is read and a presentation without a major point that has many conflicting points, I would take my notes every time.
In short, if you can’t preach a good sermon without notes, then bring your notes.