It's ok. I remember liking it when I was younger. Now, I do know a few Emilys. I'm also just not that into the -mily sound.
But it'd be ok on someone else's kid, as long as they didn't mind the popularity potential. Just because you don't know any little Emilys doesn't mean your child would never run into them.
I'd still probably prefer to see it as a middle name though.