As a guitar player, I also always appreciated the guitar in that song as well. It really added to the emotion of the piece and complimented Sledge’s great voice. Sorry to see him pass.
The one thing that always stood out for me was the end with the horns, they always sounded to me that they were a bit sharp on the notes, turned out I wasn’t the only who noticed:
Trained musicians can tell that the horns on this song are out of tune, and this didn’t escape the ear of Jerry Wexler at Atlantic Records. He sent back the original version so this could be fixed, but the fix never made it to the shelves. David Hood, who became the bass player in the Muscle Shoals Rhythm Section, told us: “Wexler thought the horns on the original version were out of tune - and they were - and he wanted them to change the horns. They went back in the studio and changed the horns, got different horn players to play on it. But then the tapes got mixed up and Atlantic put out their original version. So that’s the hit.”
I have read that Lee Atwater played guitar in Percy Sledge's touring band.