Glen Campbell was diagnosed with Alzheimer's disease in 2011, and since then the legendary singer and guitarist has been saying a long goodbye to his fans, a farewell no one wants to see end.

While the 2015 single "I'm Not Gonna Miss You," from the soundtrack to the documentary Glen Campbell: I'll Be Me, was billed as his farewell performance, Glen's longtime friend and accompanist Carl Jackson subsequently took the bold step of guiding Campbell through one final album of songs he loved but never recorded, with Glen's family assisting him in the studio.

Arriving in 2017, Adiós leans to the country side of Campbell's musical personality rather than the pop, and one can hear the toll Alzheimer's has taken on Campbell in his performances.

He sounds hesitant at times, and his pronunciation isn't as sharp and confident as it was in his salad days.

But Campbell's voice is still in quite good shape, and he hasn't lost his sense of phrasing.

His performances on Adiós are still recognizably Glen Campbell, and on numbers like "Arkansas Farmboy," "Everybody's Talkin'," and "It Won't Bring Her Back" (the latter one of four songs from Jimmy Webb included on the album), he's fully engaged and seems to be both confident and capable in the studio.

Of course, half of the joy of Campbell's best work came from his guitar playing, and he's sadly lost the ability to pick, but the studio players Jackson enlisted for the project give this music the right feel, emotionally solid but not overstated and never letting the music force Campbell's hand as a vocalist.

Adiós ultimately seems more like a coda than a grand farewell, with the album displaying a suitable modesty that suits the somewhat reduced circumstances of the artist.

But it's also a potent reminder of Glen Campbell's talent, style, and musical legacy, and this album is the recorded curtain call he truly deserves.