Good question, I don't think they are finished or at least they weren't projected to have been finished yet, so I doubt anyone has stayed in them.
If you are a Platinum and they're finished you'll no doubt receive an upgrade into them.
But if they aren't finished you'll still receive a lovely room. I was genuinely nervous/displeased when I learned before my stay that these rooms weren't ready. I thought it might color my entire stay, and questioned whether I really wanted 5 nights there without an upgrade to a larger room.
Well the Grand Deluxe rooms weren't ready, but I had a lovely room on the top floor in the main building looking straight out over the pool area towards the river. It was large, stylish, and comfortable. And I was utterly pleased.
And as a Platinum you receive complimentary breakfast.
It's my favorite breakfast in all of Starwood -- the service is outstanding, the coffee was very good, the buffet had a large variety and switched up its prepared to order foods daily. But what set it apart was that staff would bring around various dishes that weren't on the buffet for you to try throughout your time in the restaurant.
And more generally the food on-property (I didn't try Favola, the Italian restaurant, and had no interest in doing so -- other than that the pool menu is from that restaurant and certainly fine). The main restaurant which also provides room service, and is where the buffet is housed, was really excellent. Very good Lanna-style Thai food as well. Good selection of choices, very high quality, not a lowest common denominator approach to food so prevalent at resorts. Food here is sort of the anti-LM Khao Lak
Enjoy your stay and please report back!