We arrived in mid-July and it was hot in Nice and the surrounding area. The "cottage" was clean and the decor was rustic. It had everything we needed and was spacious. The view of Nice was amazing, especially at night.
About the heat. It was very hot during the day, but at night it was comfortably cool. As is noted in the listing, there is no AC. However, there are fans that kept the cottage cool for sleeping.
Also, as noted in the listing, the semi-private road to the cottage is very narrow and has very tight switchbacks leading to the parking area. Do not rent anything other than a very small car. Because of "driveway", we decided to only use public transportation which is fairly convenient, but does require a short walk up steep hills when returning to the cottage. The owner provided transit cards that you can "recharge" via your phone and that worked very well for us.
Overall, we enjoyed our stay there.