It just doesn't stand up to repeated listening. The lyrics are incomplete, the music is very repetitive, the mix is simplistic and it sounds too clean. It's interesting to listen to as a step in the process, but it doesn't work very well as a song.
The final version has that wonderful slide playing by Mick Taylor and it sounds whole. The piano playing is also much better. Having said that, I don't think the album mix is all that great, so I'm hoping the new set Singles box set will finally see the first release of the single mix on CD. From what I've heard on bootlegs it seems to be a lot better, but the quality is not so good.