Lots of discussions on HARP-L, the oldest harmonica mailing list of Internet on this subject...
Reactions from purists and people who loves the instrument are not all very kind. Perhaps noone is right or wrong...  Anyway that just make me share this video since they are playing Little Walter.
Never mind the result on "Blue and lonesome" version, Little Walter was Little Walter and Mick Jagger is Mick Jagger... The main thing I see here is this CD is a chance for the harmonica to be more present in the medias, to get more young people to buy a harmonica and discover about its history, and Little Walter... 

So I just say "Thank you" the Rolling Stones, and keep to learn harmonica as we all keep to learn and try to improve ourselves...and participate in a way to get more people learn about it Keep to be opened and curious!!! Don't forget the roots, history. Without the roots the tree is falling down. Perhaps this kind of messages is more helpful ?...