As you would expect with a 5-star hotel, everything is very luxurious, and the stay was mainly OK. However, a few things let down the visit, which came down to the hotel's management's greed.
1) The suite rooms cost $1500+ a night, yet they still charge you $7 for WiFi. They provide a slow "complimentary" service, but it's insane that a hotel that tries to build an image as the pinnacle of luxury would be so petty and ask you to pay for regular speed WiFi in 2021. Pathetic.
2) Having stayed at the Mandarin Oriental in London, I know that the service charge they add to ancillary services isn't unique to Japan. However, what is striking is that none of the service charge is shared with the staff providing the service. In London, 100% of the service charge is given to the staff in addition to their salaries. In Japan, it is added as additional revenue for the company. This purely comes down to greed because operationally, there is no reason why they can share this money with their employees. It tells me they value their Japanese employees less than their British ones.
The Mandarin will provide you with a luxurious stay but will squeeze every penny from you and their staff in the process. I want to leave a 5-star review and come back, but their greedy philosophy has left a sour taste in my mouth. I doubt they will change, but if you want to avoid the same experience, I suggest looking for a different 5-star hotel - which there are plenty.