I love EPP. I've been working on one of those "I'll finish it someday" projects for a while now - it's the Inner City pattern that I've always wanted to do, but didn't want to tackle all those Y seams. I work on it for a while, and then it gets forgotten about until I start thinking about doing handwork again.
Learning how to do EPP opened up a world of possibilities for me since so many of the patterns that I like are more difficult to do with traditional or foundation paper piecing (which I don't like at all.)
I took my project with me when I went to visit my aunt a couple of years ago, and I like how portable it is.
I have the book by Diane Gilleland and it's excellent. Another good one is Flossie Teacakes Guide to English Paper Piecing.
I tried the flatback stitch and didn't care for it - it felt awkward and unnatural to me. I tend to do a very small and closely placed whipstitch with invisifil thread, and you can't see it at all on the top of the work. I use a ladder stitch when I do bindings, so I might try that to see how I like it.