The grand rooms are the ones that are not rennovated,hence, dated.Rooms higher than 14th floor are newer and pretty acceptable IMHO. Yes, it doesn't have the wow factor as compared to other Asian properties but their service is good and location can't be beat.
As for the Diamond amenities, club access and free internet is garaunteed, not sure about upgrades but we met a couple with diamond status in the elevator while on our way to our club room a fortnight ago and apparently, they were upgraded from basic room type to a suite on the 25th floor ,which happens to house the newer suites.( yeah, in this hotel, not all suites are equal).
As for a previous post about the confusion of where to have breakfast, I think it is because they have a different promo for AMEX local versus foreign cards.As a standard amenity that comes with rate booked via the AMEX Platinum, one is entitled to 2 Continental breakfasts in-room, while for certain years (not this year though), there is a promo for Taiwan based AMEX plat that entitles a person to two full breakfast in their CAFE at lobby level.Hence, the mix-up.