We stayed here for 5 nights and loved it. The hotel is in an incredible location, a short walk to Buckingham Palace, Hyde Park and shopping in Mayfair. The rooms appear to be recently renovated and are just lovely - the bathrooms are a bit dated, it would be good to see them modernised. All of the staff are fantastic, this was some of the best service we have ever experienced in all of our travelling. Super accommodating, will even help you make reservations and purchase tickets to events. We were on our honeymoon and they placed a delightful gift of balloons and chocolates in our room, along with a handwritten card from the team. The attention to detail is exceptional.
The Breakfast is excellent, and we loved that we could order it to the room for no extra charge. We also ordered from the restaurant for lunch, and that food was excellent as well. A minor negative is that the coffee is terrible, the pod machine in the room is better - but there is a great Italian style coffee place right next door.
Overall, we will definitely stay here again and highly recommend the Athenaeum.