I didn't really fall in love with Sigur Ros until this past year. It's not that I didn't like them prior to that; they were just one of those bands I hadn't got around to yet. I really like this song by Jonsi, but have yet to pick up the album (which came out yesterday people!). "Go Do" is a great summer-y song that has all the BIG sounds that worked to cement Sigur Ros as an important band over the last decade. I have to say, when I first heard "Go Do" it sounded a bit chaotic to me. It has a lot going on, and at times the instruments and melodies seem to be trampling one another. The good news is that what your left with is a breathtaking track that sort of works in spite of itself because the melodies really are that strong.
I've posted an acoustic version as well just to showcase the great contribution of Nico Muhly, a composer whose work would be of note were he all by himself. Instead, here you get Jonsi AND Nico. The two versions show the development of the song, and work to disentangle a few of the melodies. It's an interesting contrast between the studio and acoustic versions that I think gives us insight as to how these two talented people work together, and feed off one another creatively.