The Latest Model Comes in White
That's right, Gandalf got an upgrade and it comes with a shiny new cloak and a sleek, fancy staff (we're also assuming he's probably more powerful with some new magical tricks up his sleeve, or some newfound wisdom or knowledge). And his new all-white steez gives us our protagonists quite a scare… because everyone assumes the "White Wizard" is Saruman. But instead of Saruman's craggy face, we're met with a friendly, familiar, smiling mug of Gandalf.
"Gandalf?" he ruminates, "that is what they used to call me… Gandalf the Grey…" It's like he doesn't really know who he is anymore—and for good reason. Apparently being promoted in the wizarding world doesn't just mean defeating an ancient, powerful creature of fire. You also have to take a massive, Balrog-infested journey:
GANDALF: Through fire and water, from the lowest dungeon to the highest peak, I fought with the Balrog of Morgoth. Until at last I threw down my enemy and smote his ruin upon the mountainside.
Oh yeah: and this is followed by a healing period where "every day was as long as a life age of the earth." So basically Gandalf took off for a couple centuries or more, and came back to Middle-earth "until [his] task is done." What is that task? It's not entirely clear. But Gandalf always seems to have a plan.
Gandalf the Same
So yes, Gandalf has transformed, but in many ways he's the same wizard he's always been. He's sly (telling Wormtongue's thugs not to deprive him of his "walking stick," and winking at Aragorn on his way in), full of hope and wisdom (telling Aragorn of his role to play, and that his people will need him), and always shows up to save the day (this time with Éomer and a bunch of Rohirrim riders).
It's easy to forget who Gandalf really is and just think of him as an old, wizened man with a knack for the supernatural. But Gandalf is a lesser god, a Maiar of old. As he charges down the hill towards the orcs, we would not want to get in the way of his righteous wrath.