Although I'm loathe to boost Beowulf's ego any more, this one deserves all the praise it's gotten thus far, and more:
Artistically laid-back is the best way to describe it. I LOVE the feeling I get while watching it; I can't explain it, really, it's almost nostalgia. I definitely think everyone should check this out. The effects are spectacularly integrated - in fact, most of the time it looks like the effects occur within the anime itself, and that's one way to tell that the effects have been done right. Can't recommend this one enough.