The hotel is well situated on the Allées Provençales, and opposite the public park, with the train station a short walk away. There is a good variety of restaurants nearby, and the shopping area of Montelimar is very close.
Parking is available, but needs to be booked. The hotel staff will ask what time you are leaving in the morning, as cars are often double parked to make full use of the available space. The entrance to the hotel (which is set back in a courtyard) is between a fountain and the Brasserie du Rallye on a quiet dual carriageway, and you have to drive over the pavement, so take care for pedestrians.
The hotel is very quiet (note that the hotel is closed at midnight, so make sure that you are not arriving very late), and you can be sure of a good nights sleep. The bed was very comfortable, and the standard of cleanliness was high throughout the hotel. There was a shower over the bath, and a separate toilet in the en-suite. WiFi was reliable and fast enough for my needs.
The staff were friendly and helpful and spoke a good level of English. They also were very patient when I was practising my French!
I cannot comment on the breakfast, as we did not eat at the hotel. There is plenty of choice a very short walk away!
Le Sphinx was a great base for exploring the local area, and if I came back to Montelimar, I would stay here again.