I remember reading his articles in Scientific American when I was in high school in the mid 1960s. It was fun to discover the curiosities that he wrote about each month. I found that the "math" in his articles a heck of a lot more fun than the math they taught in the school courses.
All of his writings were interesting and fun. He was quite a character. So, as the Grim Reaper has trundled him off the stage of life, I wonder who will have a similar quirky character and will replace him. To me he is like Isaac Asimov, another giant of my youth who wrote books that set my imagination on fire in my adolescence.
Here's a bit about Martin Gardner in one of the Discover magazine blogs. The key bit:
The skeptic community mourns the loss of one of our giants, but we know we’re all better off for the time we had him here.