In the books, he's a confident, charismatic leader. He has self doubt when things go wrong, but he knows who he is and he has a plan - reforge Narsil, go to Gondor, unite all men, fight Sauron. In the books, he fights off 4 ringwraiths with nothing but a couple of flaming sticks (he didn't have a sword at this point). He was courage incarnate - he looked into the Palantir knowing Sauron was looking back, and he beat him. He led his men through hell - they literally go to a crypt and recruit a bunch of undead - and it was only his will and his courage that kept all of them except legolas (who doesn't fear the dead) from losing their shit.

In the movies he's a blubbering wuss. He whines about how weak he is and how weak men are, he talks about how he doesn't want to lead, he can't lead, blah blah blah. It takes Elrond saying, "you're not getting any elf strange if you don't act like a leader," for him to shape up.