We stayed for 1 night at the Hôtel Excelsior Opéra.
The location is excellent. The big department stores are a two minute walk away from the hotel and most major sights are within walking distance. There are also several metro stations nearby.
We had room 532 which was bigger and better than we expected. It was designed to sleep 3 people, had a good size bathroom with a bathtub and shower in connection with, an espresso machine and some capsules, a good size desk and two chairs, and a stocked minibar.
The noise insulation was great. The hotel is situated on a busy road and we did not hear any noise.
The breakfast room was on the first floor. It was fairly small but did not get crowded. The breakfast had all the standard offerings: Breads, croissants, pastries, ham, two kinds of cheeses, cereals, yoghurts, scrambled eggs and tea and coffee. The items were of good quality (we especially liked the hard cheese), the selection was replenished regularly and we found it to be good value for 14 euros.
The only 2 inconveniences were that there was no price list for the minibar, it was readable only using a QR code / reader. For us, two elderly people, that was too much technology. Other people have mentioned that there should have been free bottled water in the room, but we didn't get that.
Still, we are very likely to be back as we enjoyed our stay.