I have mixed feeling about wall stickers. My wife and I moved into a townhouse last year that had a huge wall sticker at the top of the stairs. The building was brand new and the sticker was put up by the developer. It is not removable. In our view it was one of the only things about the place we didn't like. I guess we're 'clean lines' kind of people. I would certainly do it in a kids room, but all around the house, probably not.
I think you need to be careful what kind of design, so it makes the room look interesting and has a classy look.
I have even gone one step the other way, I put a lovely white flower on my kitchen window, so I could get light in....but my neighbours really can't see in from outside.
My daughter-in-law bought Tulips, placed them all along the bottom of my granddaughters little white wardrobe! Looks amazing...Just very sweet.
I think the application can be a real winner, you just need to give it some artistic thought.
Having said that we are careful 'where' they go.
Who ever came up with the idea, I think was very creative indeed.You can also change as much as you like, so it never needs to be boring.