We had 6 nights in Tokyo in July and stayed at Hyatt Regency. Not a bad experience but I will not go back for two reasons: Value for money is way too low and some of the rooms are very dated. On the value for money part; Yes, Tokyo is overall expensive but paying 2-300 EUR per night for the Regency is not recommended. The facilities (gym, pool, restaurant, common areas, etc) are dated and need a good remake. The restaurant we used for breakfast, but the selection was not impressive, nor the quality. The bar is also very, very dated.
Upon check in we got a very old room, and asked for a new. We got an offer to pay for an upgrade to a club room, we accepted and that was a much nicer room. Be sure you know where you are staying!
Was it all bad then; No, the staff was very friendly, very helpsome and certainly very capeable. Overall I would rate the hotel 3 stars with a plus for the staff.