I saw it in 3D last night in New York (I'm across the Atlantic visiting my brother for a week, and this was a sterling opportunity). I agree that the 3D effect was used expertly in this feature to provide immersive depth and make a convincing case that this fantastical realm actually exists.
For those interested in where it's set, it takes place in Ashland, southern Oregon. I recognised the Shakespeare Festival that was played to great comic effect while Coraline's Proper Mother was in town shopping for uniforms. Ashland holds a Shakespeare Festival every summer.
I'm extremely pleased that Coraline has been doing such decent box office. It was a risky production for an indie with high startup costs, and it seems to have paid off surprisingly well. Deservedly so, since it is a sweet, affecting, superbly crafted film. It's a hair's breadth away from beating The Nightmare Before Christmas' combined domestic tally. It's still in 3D theatres until Friday, when Monsters Vs Aliens finally succeeds where Jonas Bros failed and kicks Coraline out of 3D for good.