I've studied Isshinryu and earned the rank of Sandan. Personally, I am not convinced that, in all applications, the vertical punch is better nor the blocking method is better. I have no proof but I believe that the style was designed as a martial art specifically for the U.S. Servicemen working with Shimibuku. Shimabuku developed techniques that Americans would better adapt to because that is the way that they punched, blocked and kicked. It seems to me almost as if the Servicemen told Shimabuku, teach us karate but we want to do it this way. In addition, some of these servicemen came back as 7th dan after less than two years of study and yet, their students spent years earning a black belt (this is documented by the way so I am not making this up). I enjoy some of the redesigned Kata of Isshinryu and I also enjoyed the weaponry part of the style (although I think that they could have developed more Tonfa kata to go with it. If you like it, stay with it, enjoy it. Don't worry about popularity of the style.