What is Gandalf like?

Gandalf is a wizard. In many cases, he has helped Bilbo and the dwarfs, but many other times he has disappeared. We haven't heard enough about him to make an informed description.

Gandalf is very wise and trusted but also very misterious unpredictable. He is trusted and respected by many people like hobbits and elves as well as dwarves. He seems to be very important and reliable. Until now, he always gets the dwarves and Bilbo out of trouble. A few examples: he saved them from the trolls, he got them a place to stay (elves), and he saved them from the goblins. He seems to be a real asset to the fellowship.