Suggest it better not to judge them on their Youtube clips as seeing them live far outstrips their screen persona. I saw them at Rivelin Festival last year and was quite impressed I have to say but there were others with me who found their style a little unusual and asa traditional 'Folkies' were unhappy to accept that they are good.
As others have said here....some like them some don't..but whatever anyone thinks...success proves anything of quality to a majority... and they are successful!
Best wishes, Mike.