I don't even see the point of a single at this stage, and especially not Song for Someone.
U2 are not at the point of their career where they are going to get a massive chart hit, especially not the third single from an album that was free. If the purpose of the single is more to get a bit of airplay to promote the tour and sell the tickets, then I really don't think a cliche snoozefest is going to do the job. Get people in the door by getting them excited and their blood pumping. Volcano or Cedarwood Road fit that bill.
But hey, whatever, release another shit song as a single. That seems to have been U2's general approach for a long time now.
On my first listen through of the album back in September, "Song For Someone" was the one that stood out the most for me. Its got beautiful guitar by the Edge and soaring soulful vocals by Bono. Your more likely to get members of the general public into this song than any other on the album. Its under 4 minutes which radio programmers love.
Its not the best song on the album, I prefer Iris, Crystal Ballroom, Invisible, and Volcano over it. Still though, one of the better ones.