The Cumberland is conveniently located right around the corner from Marble Arch subway station. The hotel is in good condition and has everything you would need. The rooms are well-sized and well-equipped with coffee machine, kettle etc.
The downsides are that the hotel is very big and the elevator system is not programmed to handle the amount of people. That means, people crowd in front of the elevator and you might need to let them go (as they are full) a few times before you finally get in. Luckily, we were on the first floor so opted for the stairs very often. However, staircases are few and can only be used to go down; to go up, you’d need staff to open the door for you.
Similarly, the breakfast area is huge and has a good selection of food, but it is laid out that you end up lining up multiple times to get seated and to get food.