...with the smart case, how can you protect the back against scratches? would be nice if apple just redesign the existing case.
Well, I can't speak for everyone, but my iPad has gone essentially case-less since launch day last year and it doesn't have a scratch on it. I had a couple cases on it from time to time, but they were short-lived things. Hated the way they felt. It's been naked I'd say 95% of the time and mine doesn't have a single scratch on the back. Granted, I'm careful with it. Even the plastic Apple on the back is like new.
I do keep it in an Incipio Underground Envelope when carrying it around (generally in a Timbuk2 bag,) but in use, it's naked. I just don't see the point, I guess. Makes it bigger, heavier, uglier, and feels awful. The nicest thing I've seen is Apple's "smart cover." So if you're a gentle user, don't worry about the back and enjoy your new iPad and cover. Personally, I wouldn't even bother with the smart cover, either, as it'll get in the way. But I can understand why some will want it - the fold up stand design is pretty cool.