We booked Chateau du Sureau because it was the only good hotel in the area. The Ahwahnee is the alternative and gets pretty bad reviews, and some cottages I had found were fully booked. The chateau is very nice and the service is excellent - the staff really do go out of their way to be helpful and friendly. I can see that some people might find this overbearing - it's a small hotel and they do try to make people feel at home, so it's a very different atmosphere to a big 5* hotel. If you like cosy, then this is the place for you. The rooms are indeed a bit small, in keeping with the chateau theme. The bathtub was too deep to get into and out of comfortably, even for a young person, and there didn't appear to be any central heating, though there was a fireplace in the room.
The problem is that Oakhurst is not a very nice or charming place. When we made the reservation, we planned to eat at Erna's Eldeberry restaurant (associated with the hotel) and then try other places too, but there is absolutely nothing in Oakhurst other than chain restaurants (Pizza Factory etc), a dodgy-looking Chinese and the like. There are some better restaurants further afield, but they are at least a 20min drive away, down winding roads that are unlit at night. The food at Erna's restaurant is good, but again I felt it was overpriced at $95 per person for the prix fixe menu plus $75 each for matching wine.
Despite Oakhurst being only 15m from the Yosemite park entrance, it still takes a good 25-30mins to get there because the roads are so winding. Then it's a further hour from the entrance to the valley - so Chateau du Sureau turned out to be far less convenient for Yosemite than I had expected.
Overall, it's a good hotel, but I am not sure it's worth the price. For c$500 a night I would have expected quite a lot more. The problem is that there doesn't appear to be an alternative in the area.