I wonder if First Editions will actually be worth anything some day. I don't know how many copies were published in the first run, but apart from the first maybe one or two books, I would guess it was a heck of a lot. The reason First Editions of Moby Dick are valuable is because there were relatively few of them to begin with. That being said, I have first editions of all the HP books (including one FE of the English release, so a genuine First, really) and I'm hanging onto all of them in part for precisely that fact, just in case I'm way off the mark.
Related to the books themselves, when the first book came out, I was roughly the same age as the characters. I read each new book right when it was released, and while the age gap grew a bit over the course of the series, I felt like the series and its young characters grew/matured as I did. I think that made me enjoy the books more. I re-read a couple of them a year or two ago and DID still like them quite a bit still, to be honest. But I'm not sure how much of that is due to a nostalgic connection I feel for the series. For someone whose never never read the series but is generally interested and liked the movies, I say go for it. The books can be purchased cheaply used or on Amazon, the longest of them won't take you more than a week to read, and you'll be in on one of the biggest, most successful cultural phenomenons of all time.
