Had beginner lessons with him a while back when he was still at Bishan range. Was already playing then but joined a group of 3 other friends who were picking the game up for the first time.
Technical-wise, I felt he was just as competent as other coaches I've had before. He would go through the basics with us as a group, but also took the time to correct some bad individual habits of mine.
Style-wise, he's a friendly instructor who puts you at ease and takes the stress out of learning. There are some coaches who give really impressive demonstration swings but who aren't good "teachers". Garry is probably one of those who can teach.
Just my personal opinion, hope it helps.