I can't recommend this place highly enough. We stayed here for five weeks in October/November and loved every moment. The owner is extremely responsive and sincerely cares about the quality of your visit. The location is ideal - downtown Napa has all the amenities of a wine country town with none of the Disneyland atmosphere you encounter in places like Yountville or St. Helena. You're within walking distance of at least a dozen excellent restaurants (including the fabulous Oxbow market), but my wife and I were also able to find exercise facilities that worked well for both of us (try doing that in Calistoga). Whole Foods, Trader Joe's, BevMo, Walgreen's, etc. can all be found within two miles. Being on the south end of the Napa Valley also gives you relatively quick and easy access to Sonoma County wine country.
The unit itself is stylish and comfortable, just as it appears in the photos. We cooked often, both inside and on the gas grill on the lovely, private rooftop deck, and found everything we needed in the well-appointed kitchen. The bed is very comfortable, and we never heard a single sound from the adjacent units in the building. There is a one car garage, and we never had any trouble finding parking for our second car outside the unit on Main Street.
I can't imagine a better choice for an extended stay in wine country or a long business trip.