John Prine is a master at taking something somewhat simple and turning it into a really enjoyable, poignant piece. Most of the time this is due to the lyrics he comes up with but his guitar playing can be interesting too. In spite of the fact that he only uses his thumb and one finger to pick, he comes up with nice embellishments many times.
All The Best is played in the key of G, like most of his songs, capoed at the fifth fret, or wherever suits the players voice, and includes one of these embellishments that might prove a bit challenging. Otherwise the song is what I would consider generic fingerpicking. If you have a good command of alternating bass techniques you should be ready to add this tune to your repertoire.