I'm definitely a fan of the double J! I usually go to the JJ near my office in the university area, but I got to hit up the Matthews location after running some errands on an off day. I must have missed the lunch rush, but I walked in, ordered and was out of there in 5 min.
Though this location is missing the noise and energy of the other locations I am used to, the sandwich was good and what I was expected and they were very proficient in getting me on my way to a full belly and back to the office.
Location didn't really have a lot of tables to sit down and enjoy the awesomeness of JJ's, but there were enough. The shopping center is fairly busy so parking looks to be tight. I didn't really see that many drivers running in and out of this location, but I was only there for 5 mins (probably not enough time to judge how busy this location is).