Well, I really liked the game as a kid (unlike the movie, I found it pretty underwhelming) and yeah in my rating today there is a nostalgia bonus.

The soundtrack is, in my opinion, pretty fine. Nothing special, but not bad. It might get a bit annoying to hear the same tracks over and over.
Like your typical move tie-in game on the GBA it uses stills from movie and text boxes to tell the story. Interesting enough that the intro and end of the game are low res versions of movie scenes.

The gameplay is more or less a typical platformer where you solve smaller puzzles with each characters abilities, collect totems and go to the end of the level. Sometimes there is a hunting level where you have to escape from the brother of the protagonist.

"Emily is Away Too" makes you forget you are playing a game and makes you feel like you would chat to people from your high school. You can not make so much wrong, sometimes you need to remember something like someons taste in music. However you can't lose the game, but make it to a different ending, .
A few times you need to react quick in two chat rooms, which can be annoying if you want to respond thoughtful.
The best feature are the old looking YouTube and Facebook pages which will appear during the chats.