My wife and I stayed at the Gristmill for three nights in July. On balance, we were very pleased with our stay. The Gristmill is a cross between a B&B and small boutique hotel. I describe it as "eclectic" because the properly is a collection of connected buildings, the main portion of which is a "U" shaped area anchored by a turn of the (20th) century gristmill. As one would expect, the buildings that comprise the property are older with all the good things (character) and bad things (window air conditioner, odd smell in our room) that come with age. Still, we were quite comfortable.
A Principle draw for the Gristmill comes from its location (lovely spot in Warm Springs), and the relaxing (read a book), cultural (Garth Newel Music Festival) and recreational (hiking, etc.) activities available in the area. The second draw from the Gristmill is the quality of its restaurant. Simply, GM restaurant is exceptionally good. Indeed, some dishes (for me, the French Onion Soup) are among the best I have ever enjoyed. The wine cellar invites one to linger to the point of missing courses as these are served. The restaurant's very small bar is quite friendly and provided the opportunity to chat with a couple of locals who offered great suggestions on area "see and do".
Recognizing the GM is a bit eclectic and a bit old (both characteristics in good and bad ways), I highly recommend the properly.