Someone once said that the world is complex, dynamic, multidimensional; the paper (in this case- wallpaper) is static, flat. How are we to represent the rich visual world of experience and measurement on mere flatland ?! Well, every Design depends largely on constraints, so It seems, sometimes, constraints and limitations can be an advantage…
Here are a few, who seem to manage designing a whole new world out of this 2D material:
As EIJFFINGER manage to show, you can “change the world”, insert a different atmosphere and colours or play with various dimensions of the room, just by putting up a wallpaper…:

Hay, and if you really want to, there is a great way to go back in time…straight to the 70’s with retro chic wallpapers:

The wall decals are a great replacement for the traditional wallpaper. If you’re not so sure, you want the hassle involved in putting up a wallpaper and if you prefer the graphic approach (though, there are great wallpapers with beatiful graphic designs), here are some examples:

If you have no problem with the hassle, but just can’t afford the “real thing”, you can create the “wallpaper effect” using stencils and the end-resualt would look just as nice: You can also try the Roller- stencils:
There are endless ways to design your walls- all you've got to do, is start...

Anyway, I hope you enjoyed this post.