In my opinion, Otis Spann is the greatest blues pianist ever. He was a mainstay of Muddy Waters' band, played with all of the blues giants, and made some fine recordings as a frontman, as well.
Of the albums put out under his name, this one is my favorite. It features tracks from 2 albums plus some previously unreleased tracks. Tracks 1-5 are absolutely stellar (although they feature no guitar whatsoever), with great blues piano and soulful singing from Otis -- "Burning Fire" and "Sometimes I Wonder" are some of the best blues vocals I've ever heard.
Tracks 6-15 are excellent for the most part, except for 2 Hammond Organ songs. I'm not a fan of the Hammond. The weakness of the album are tracks 16-18, which were probably previously unreleased for a reason.
But on the whole, this album has some of the best blues piano you'll find.