I'm in the middle of a 3 night stay, deliberated between it and the Hyatt Regency Churchill based on reviews here. Overall, I'm happy with my choice, though I'd have been unpleasantly surprised by the room size had I not known in advance.

I think this property is close to the level of most of the Park Hyatts I've stayed at (most recently NY and Milan), except for the negative of the room size. The rooms are relatively new, very nicely decorated, well appointed with all the amenities you'd want/expect (Nespresso, even a washlet in the bathroom). The public areas are beautiful, there's a nice bar with great service, Globalist breakfast is a la carte (restaurant only, no in room), with a decent selection and very good food quality. Service so far has been excellent, though no turn down service is offered at night. The location is also very central, close to the Charing Cross tube stop and Trafalgar Square.

The only real negatives are the room size (small enough that if you have more than one suitcase you'll need to unpack because there's nowhere to put the second one) and the lack of an in-room option for Globalist breakfast. I was upgraded to a city view room but I would not pay for the view; it is not any better than a courtyard view or no view.

Relative to other similar properties in London, I think Great Scotland Yard is a good value if you're not using points. The Sofitel St. James, also a great property, is a few blocks away. I'd say the two properties are comparable, though the higher category rooms at the Sofitel are larger, but Great Scotland Yard is half the price for the days I checked. I'll take a somewhat smaller room for that kind of savings.

They removed the 5% discretionary service charge quickly and easily when I asked, for whatever that's worth. Agree with others here that it's deceptive but at least it's easy to get rid of.

I'm planning to return for a family trip later this year; overall, as I said above, I think there's a lot to like here.