Just about at the end of Melee Island in the special edition now, and I have to say the work is really impressive. While I love the original to bits, when you flip between the new version and the old version the sheer lack of ambience and whatnot is quite striking. The fact that every scene now has (at least subtle) animation and ambience adds a lot to the atmosphere, and having not played the original in years it's great rediscovering all the dialogue with voices. Also a great job has been done of revamping the music and such.
What's really cool is how the remake opens up the game to new audiences as if it were new. My younger sisters have been playing it and loving it, whereas with the ancient-looking original they'd never have even considered it.
Some guy on another forum I use has been kind of taking the piss, though. Whereas LucasArts basically just redrew the background art and upped the resolution on the visual side of things, this guy has been doing some crazy experiments with 3D projection where he basically gets the original concept art (only a few were released) and then models it. Using techniques I can only begin to imagine the result is kind of breathtaking — especially the second video. Hit HD and full-screen to really appreciate it.