My dad was a big fan of Isaac Hayes and indeed a lot of the other Stax artists, as a result, I grew up listening to a lot of music from the Stax label.
So far as Isaac Hayes is concerned and film soundtracks, this really is worth buying. Isaac Hayes shows the depth of his creativity by producing an original soundtrack that has everything in it...vocals, instrumentals, lots of strings, horns, excellant rhythym section etc.etc.
Most people will be aware of the 1st track 'The Theme from Shaft' but all the others are great as well. My particular faves include 'Soulsville', 'No Name Bar' and 'Bumpy's Lament' which specifically has been sampled/copied by numerous other rnb and rap artists.
Overall, it's a masterpiece and thoroughly deserving of its Oscar. As for the film........well the less said about that the better!