But how easy is it to replace. A neat idea, but I have a new home and don't want to do something permanent like this.[/quote]
For walls, it only goes up with wallpaper paste so it's as easy to take down as any other paper. there is no need to apply urethane over the top since, probably, no one will be walking on it! To apply the paper, you simply put wallpaper paste on the back side of the paper you are applying then smooth it on the wall, overlapping pieces slightly so no sections of the wall show thru. I just use my hands to smooth the paper on the wall, no need to use fancy wallpaper tools unless you really want to. It's messy, but fun! Kids would probably love doing it.
You can use either paper bags or even craft paper you buy on the roll. Another option is to purchase what I think is called "plumber paper" at a hardware store. This is heavy duty construction paper used to protect floors in areas where work is to be done. This comes on large rolls, is relatively cheap and can cover a lot of area plus it usually comes in a brown with a slightly reddish cast, so has a little color to it.
Rip the paper into medium to large size pieces..the bigger the pieces, the fewer you need to use to cover the wall. I normally use craft paper on the roll and use pieces with the cut edge to line the perimeter of the wall I'm going to cover...don't have to trim any that way, just line one straight edge up with the last one! Once the perimeter is completed, then start building the interior by slightly overlapping the previous piece with the edge of the new piece.
Based on experience, if you're doing a large area, let part of your work dry completely before proceeding with the next section. When the wallpaper is applied, it can slightly stretch the paper which, when dry again, can shrink back to regular size..if you do a large space and don't let sections dry first, you can have parts of the paper peel up as the shrinking pulls it off the wall. But even then, it's not a disaster, simply tear off the part that has peeled up and apply new paper over the old to cover the hole.