I read this when it came out in 1991. At the time, there was nothing like it. What's not to love about pulling someone else's letters out of little envelopes and reading them? The mystery, the pretty art, the satisfying voyeuristic aspect; I liked it all. Also, I was very big into writing letters in those days, with my expensive stationery, my fountain pens, sealing wax. Ah, the days when I had lots of spare time. Anyway, I remember these fondly and still own the whole series.