Big Ghostbusters fan, but it wasn't until somewhat recently that I found out this book even existed. Yeah, some sellers ask a lot for it, but I was able to find a decent copy on eBay for a reasonable amount. And yes, the book is available for free as a pdf, but I wanted the actual paper. I guess I'm just weird like that.
I enjoyed the read quite a bit. If you didn't know, it is the shooting script for the movie, with annotations and trivia in the margins. There are a lot of production photos (which I wish were color) included as well. There is a short color photo section at the end, though. A lot of the stuff I knew already, but a lot of the notes are direct quotes from the creators, which I liked. Over 200 pages, and it was a good read.
If you're not a big fan of the franchise, you can skip it. Even if you are, I'd check out the online version for free just so you can be sure it would be worth the investment.