The lyrics are pretty average for this style of music, and very on par for Miley. I guess there is emptiness there too, by way of not having much to say.
But it was mostly the sound of the album that did it for me. The whole thing sounds so thin and fragile. It's like if you took a 20 second stripped back instrumental breakdown and turned it into an entire album.
I see a bunch of people here complaining about how long it was, but it seemed like the perfect length to me. This is the kind of album where each song is good on its own merit, but the whole project comes together as one warm, vibrant and dreamy soundstage. It's the kind of thing that you can get comfortable with and not want to end after just 30 minutes.