"This is a great location for us as international travelers. We tend to book a hotel at the airport before our departure to make things easier when leaving, no dealing with rushing to the airport.
The staff here are amazing and helpful, even with my little Japanese. They spoke English but shared with me how to say things in Japanese properly.
They held our luggage the morning of check-in and and late into the evening after check-out with issue or additional cost.
My only downside is no washer/dryer in unit. They're available in the hotel and what's cool is you can see on the TV in the room the status of the washer/dryer, available or occupied with time remaining. Although it's helpful to see, that means staying put and waiting for availability. It's not guaranteed that it'll be available from the time you leave the room to where the machine is located. So I'd the hotel is booked, which it was for us, nearly all the machines were occupied whenever we checked. I'm sure it's great when it's not so busy, but we'd rather be exploring then staying put in our room and then race to a washer/dryer when on e becomes available.
Over all, we enjoyed it and Haneda Terminal 3 has a lot to enjoy as well. It's also easy enough to jump on the monorail and connect back to the local trains of Tokyo."