I came to South Beach to celebrate my birthday with my best friend; we stayed in a Couture room, which indeed had a king sized bed. It was clean, modern, and i LOVED the mirrors everywhere (two girls CAN fight over a mirror). The location was great too, since it's not right ON Ocean Drive (so the noise from the strip wasn't an issue) but you're close enough to feel as though you're there.
The staff was absolutely wonderful, friendly and helpful. The bellhops, who also worked concierge, were super attentive, helping me pick the best spots to celebrate my big day (whether it was the best spot on the beach to get a tan, the best place to get food, to party, etc.).
Only reason I didn't give it 5 stars was because my room faced the alley and the garbage truck woke me up at 7 am (after partying all night, NOT ideal) on a Saturday morning. Also, I was charged for using the mini-bar, which I didn't. However, they were very gracious about this and quickly took the charge off my card.
I was able to see what people have said about the paper thin walls, but I only heard other guests during the day; they never woke me up in the middle of the night, so it wasn't an issue for me at all.