Just came from a short stay and I was extremely impressed.
It's a large hotel with typical W trappings. The service was excellent. Front desk, valet, restaurant staff were all engaging and competent. Pre-arrival correspondence and check-in/-out were smooth and efficient. Seems like it could be the opening "A team."
They upgraded me (Titanium) to a very large suite with a wrap-around balcony facing the ocean. The room had retro furnishings that were very comfortable like always at W, a huge bathtub kind of in the center of the room (like some other Ws, there is no separation of the bedroom from the bathroom), and good lighting.
The pool area is outstanding. There are numerous different seating options, including pseudo-cabanas that are not enclosed but covered and sort of on pods, surrounded by shallow water, with two chaise lounges, two chairs, and a small table on each. Not sure if there is a separate reservation/charge for these, but it didn't seem like it. Like most or all hotels in Qurum, the beach is public with no services. To access it, one must exit through a gate from the property, cross a path, and go over or around a hedge. The beach is pretty solid, though, with clear water at a perfect temperature on a July day, and decent, clean sand interspersed with bright-colored pebbles. It's not Seychelles, but the beach compares favorably to most on the southern/eastern Arabian peninsula in my opinion. The showers to rinse after coming from the beach are especially nice. I didn't visit the spa.
The best part, which I don't recall ever seeing before: the pool is open 24 hours. On Friday from 2:00-8:00pm, they had a party with DJ, etc., with an OMR 15 (around $40) cover charge. I didn't partake and don't know whether the pool was otherwise accessible during this time.
Breakfast, which they gave me, was solid but not spectacular. The food quality was high, service great, but selection could be better for a hotel of this caliber. No pork unlike some hotels in Muscat.
The Living Room lounge off of the lobby is gorgeous. It has indoor and outdoor seating areas and a great menu. They post lots of rules, like couples only in certain times, though affirmed that this doesn't apply to in-house guests. F&B overall is still a bit thin. The only other restaurant open besides the all-day dining and poolside cafe is a steakhouse, without its own bar, that looked pretty good. The Buddha Bar lounge, they said, is set to open in mid-September, as is the Wip Lounge, which will be available to high-status guests. (According to the web site, a Chinese restaurant is also coming, and they serve dinner by the pool as well.)
P.S. The property seems comparable to the new Kempinski at The Wave. I visited the public areas there and was also impressed. It's a real contrast to the W; the lobby and grounds are strikingly austere and a bit more elegant. The restaurants looked a bit better too -- I visited the buffet, cigar lounge, and Zale Beach Club & Lounge, and there are also Thai and Arabic restaurants. These seem like two great upper-mid options between the tired Grand Hyatt and Intercontinental (and Shangri-La, which seemed tired even when it opened) and the luxury properties like Chedi and Al Bustan (though these are a bit tired, too, I suppose, though I have never been to the Chedi -- just some reviews indicate this). Along with the new airport, which might be the nicest mid-sized airport in the world right now, good to see Muscat upping its game.