I have known and listened to John for years and love his playing. He is one of the most gracious and unassuming human beings you will ever meet and one lesson will leave you with enough material to work on for a year. He is always pushing the bounds of harmonic knowledge, and knows the guitar and its possibilities cold... open string voicings and melodies, those amazing tight voicings he's so good at... Seems most great players know of him and respect him hugely, but his music isn't as approachable as some, which keeps him out of the limelight. But, he will NEVER compromise. He hears things a certain way, and will simply not "dumb down" his music.
That being said, sometimes you don't appreciate the level he plays at until you hear him on a standard. Amazing comping skills, as well. Just an amazing human being, all around. I wish I could instantly make him famous, he deserves it.
Some great choices for listening to John: the first ''Scenes" album, Banff Sessions, duo album with Frank (?) Haunschild, Resonance, the older stuff with Dave Friesen..... Take any 5 minutes of John's playing and transcribe and analyze it, incorporate it and it will move you ahead musically 10 times faster than most other studies of jazz, I think, even if you never try to sound like him. Try it!
Argue for your limitations and sure enough, they are yours.