Ooh I love this! Very summery.
I bought a shirred top recently and was hoping to try my hand at shirring something similar.
As for adding more interest, I think its cute as it is now, but my top has this interesting addition you might be interested in. They have basically threaded and looped some thicker thread (almost like a very thin wool tbh) through the shirred stiches to make a subtle pattern. I'll try and find a photo, I'm afraid I don't know the technical term.
Does anyone else know what I'm on about? ^^;;
EDIT: Might be faggotting..? http://en.wikipedia.org/wiki/Featherstitch