Movie
Gandalf and Book Gandalf are 2 totally different personalities.
I wrote several times on this forum that movie Gandalf reminds me of a good old grandpa, or Santa Claus type of character.
Book Gandalf wouldn't stupidly hit his head on the
hobbit roof (neither
Tolkien would make such a low humor scene).
Book Gandalf ALWAYS knows what to do in critical situations. He doesn't ask
Frodo to decide if they were go to the
Moria.
He makes decisions by himself, and he have authority to do it, and nobody in fellowship is daring to question his decisions, and if they (rarely) do, they are beaten right away with Gandalf perfect argument (this is why I say he is incredible rhetoric).
He is
the one that solves the Moria door puzzle, not Frodo.
He sometimes doesn't even want to argue with other characters, as that would be just a waste of time.. I felt like... after he realized
Saruman have betrayed, he was like... bored.. haha ... like... "Ok, you have me as a prisoner, but don't bore me please".
He have incredibly strong personality.
Book Gandalf stands his ground in confrontation with
Witch King like a statue of the Gods, he doesn't being beaten up.
Book Gandalf always have some information hidden. He never reveals everything he knows. He just know something that other characters don't, that readers don't, and when he reveals some of his thoughts (like when traveling with Pipin on
Shadowfax), you get to admire him even more, because everything he says makes perfect sense, and he is always one step in front of
Sauron.
Tolkien wrote that whenever he appears, he sparks energy in others... only energetic people can do that.
Movie Gandalf is pretty much opposite.
He is always tired.. weak... smiles too much... he is weak in verbal confrontation with others... the kung fu stuff fighting in action scenes, only makes him less believable....
The only scene where I liked him, is when he starts yelling on
Bilbo, and he became higher, and more threatening, while lightning changes...
That is how "real" Gandalf should behave...
You just don't mess with him.