I was stopped last night as I left choir practice by a woman who was jogging by. She wanted to tell me she'd read my book and liked it. That's very nice.
I live in a small town, and everyone knows I've written a book. Many ask about it, many say they read it and liked it. The reason this experience was different is because the woman took a minute to say exactly what she liked. That does two things: it lets me know she isn't just being polite, and it gives me specific information about what I do well.
The odd thing is that the specifics are so different for different people. One person tells me she loved Eleanor, a secondary character. Another loved the tiny bit of mystery that blends into the romance of the story. One man praised how I caught the Scottish way of speaking, and a woman at church loved the inclusion of an Arabic woman, how her lifestyle fit and didn't fit in eleventh-century Scotland. The woman last evening said what others have said: she had to finish the book once she'd started it because she wanted to know what happened to Tessa.
It may sound like I'm bragging, and maybe I am, a little. But the point is that specifics mean more to an author than just "I liked your book." I suppose it's true with everything: when you tell me exactly what you liked, I believe you. I carry away with me a clear idea of what one person responded to in my work.
I suppose it would work with criticism too, but let's not go there yet.