My experience staying at Heritage Collection South Wing was overall positive, although mobile key can be a bit fiddly, which I suppose partly depends on the Bluetooth/NFC connectivity of your phone.
Great location, walkable distance to sites of attraction and MRT stations. My room at level 3 was surprisingly well soundproofed despite being surrounded by bars and restaurants late at night. My shout out to Mary and Naw for their impeccable customer service. Cheers.