I just got one of these from a BPL member. I was car camping with my girlfriend at Lake Tahoe with predicted lows of 39* and broke out the Shenandoah at about 3am to give it a test run. I was in a 2 person Coleman tent sleeping on an air mattress. Clothing was a Smartwool microweight crew + adidas nylon pants + smartwool liner socks. With a fleece beanie on top, I was plenty comfortable, so I'd say it's accurate to its 40-45 degree rating. No problems with cold spots at the sewn-thru seams. Top-notch quality. Reguular (76") size is just right for me at 5'10" If I hadn't bought it used though, I'd probably go with an 86" b/c at home I like to pull the comforter up around my head in sort of an improvised hood. The 76" length is just a couple inches too short for that, but the 86" would likely be perfect.
I have wide-ish shoulders, so I was concerned about the 48" width of the quilt, concerned that as a restless side-sleeper I might be letting in drafts every time I moved. I didn't really find that to be a problem, but then this is a warmer weather quilt so 'cold' drafts aren't as big an issue.