I have loved the original song for a while and I have to say I do not rate this cover at all.
It is a worthy cause but they sure picked a difficult song to sing. Bono sounds weak and reedy, and Alicia has too much warbling for my liking (even though I like her other work, it doesn't fit this song). It is virtually impossible to improve upon Kate Bush's ethereal tones in the original.
I don't think the song suits either of their voices, even though they both have fantastic tones with the right material.