Earlier quoted context omitted.
He's extremely mysterious and in a good way. He is one of the only characters able to just casually put on the one ring with seemingly no effect and then give it back immediately afterwards. I think he gives off eldritch horror vibes, but in a mostly benevolent way. If everyone else were ants, he would be an etymologist intrigued by our behavior or something.
> He is one of the only characters able to just casually put on the one ring with seemingly no effect and then give it back immediately afterwards. OK, that's fair enough. But to my mind, this is just a setup that cries out for an explanation that never comes. It's a major flaw in the dramatic structure of the narrative, a bug not a feature. But I guess we'll just have to agree to disagree about that.
As a kid first reading it, I feared the barrow wights as much if not more than the Nazgul.
The whole aside was to show that the hobbits had truly "left the Shire" and that perils lay along the road in any direction they might turn. But, again, there were allies or, at least, guides all along that road as well.
Bombadil and Old Man Willow are a foreshadowing of the Ents to come.