3.5 for sheer charm, though a little of that comes from hearing the author's voice in my mind, recollected from the "Cucurbitology" episode of the Ologies podcast. I recommend listening to that first (or possibly only, because the most interesting tidbits from this book are recounted there).
First and foremost, this is really a food book. Fully half its length is taken up by recipes (a couple of which were included twice in different categories). When you check the citations (yes, yay, there were some citations), most of the author's sources also revolve around food. E.g. Foods of our Forefathers; The Green Thumb Cookbook; Cooks, Gluttons, and Gourmets: A History of Cooking; Eating in America: A History. There's a couple horticulture and gardening books in there, plus the references for folklore...and I guess to be fair, it IS a food product first and foremost...but think of the history and growing tips as the long lead-in the recipes and you'll be happier.
The information is rather inelegantly delivered, with abrupt transitions and once a repeated twice-in-one-paragraph comment about the lack of refrigeration (and facile opining about maybe that's why they used so many spices). The folklore stories are served up as, basically, "here's a story I found interesting: [page of quoted text, twice in strong old timey AAVE]." Repeat. Repeat.
I notice that the vampire pumpkin/watermelon mythology didn't get a mention, and dulce de calabasas just snuck in at the very end, despite being a traditional holiday food for Dias de Los Muertos. But we DID get a list of pumpkin varieties that read like the blurbs from a seed catalog (no pictures).
All in all, I'm sad to say I didn't love this. I enjoyed it, but I kept wishing we had a little more scholarly and little less folksy charm, and slightly more polished writing. (Cough, "Pliny the ender" typo, cough, though really the aforementioned transitions between source grabs) And as much as I love a good history, I found myself wishing for just...more. More depth, more explanation, more cultural examples.
So good news, you don't have to be an obscure pumpkin nerd to enjoy this book. Gardeners and home cooks will be able to take advantage of all the growing, harvesting, processing, storing, and cooking tips.