Do not base your decision on whether to buy this album on whether you have the songs on some other album. The sound quality of the songs on Mothership is so much better than any other album of Zeppelin you may own that you should add this album to your collection. I don’t know if it is the new technology available or if the band members spent more time on the remasters, but each song on Mothership sounds much better than what I have on their studio album versions or on their previous remastered collections. I feel bad for the reviewers who are not getting the CD because they have the songs in other forms. Those poor guys are thinking that the same old songs are just being burned to on a new CD. Their loss. I also feel bad for the people who just get the MP3 version of this album. You lose out on the improvement in sound quality if you don’t get the actual CD of Mothership. You only buy Led Zeppelin because they sound great, so you should get the album that makes them sound the greatest.