Since this is a forum, and you can give opinions on a forum, I first, am going to respect your opinion of your Macbook Air of it looking quite nice. I on the other hand, think that is the stupidest thing one could possibly do to their nearly $2,000.00 laptop. I mean, the lines aren't even filled in all the way? Maybe if more time had been taken into it and your sister had sketched the lines in pencil and then carefully colored them in completely it would have looked better, but IMO it just looks like trash. It looks like a doodle that belongs in a 10th grader's Chemistry notebook.
As stated previously, just an opinion.