A few quick thoughts.
Let me begin by saying this looks like a pretty good build. It's certainly kept close to the theme well enough to be effective. You have a good mix of flyers and some spot removal if you need it.
But I see two things that could be improved.
1) You're sitting with almost HALF of the deck as lands, and yet you have no additional means to draw or speed up your drawing. Since your curve tops out at four (with the exception of one card) that translates into a LOT of dead land draws, turns where your opponent won't just be sitting around. Sadly, white doesn't have a lot of help for you here, or at least nothing that's really coming to mind. Even something as simple as Jayemdae Tome or Trading Post (if you prefer a little added flavor/flexibility) will help in this department, as you won't be short on lands by any means, but speeding up your draws will win the game.
2) For as powerful of a mechanic as exalted is, it has a TON of flaws. Most notably being, the chump blocker. Without trample, a single Fog Bank brings this deck to its knees for the most part and then you're simply trying to overrun the enemy, which, to be honest, isn't the goal here and could be done much more effectively with a different white build. BUT, white does have something in spades that would work well with exalted that can influence the game in another direction - lifelink. Then when you swing and your creature gets pumped to 20/20 and chump blocked, you at least gain 20 life, putting you further out of reach. Options here are numerous - Ajani's Sunstriker and Seraph of Dawn both come immediately to mind. That then guarantees you're getting SOMETHING out of your exalted attacks until you can land Akroma's Memorial.
I don't imagine any of those changes would cost more than a dollar or two in total... so that should help.