My wife and I got a sky couch from NZ to US a couple of years back and it worked quite well for us, but as others said, you have to be small (we're 5'7 and 5'3 and both slim).

What we did before the flight was make up a mock up seat on the floor at home, using the couch and coffee table as seat backs to create a space the same size as the skycouch. That way we could try it before we used it to find the most comfortable position. We did find it got quite warm (as you are very close) and my legs had to be bent in to avoid going into the isle. But we both got a good amount of sleep.

On another leg we tried sharing the sleeping, so we each got more space, and a better sleep. One of us sat in the isle seat, and the other slept on the other two seats and put their feet on top the other. This worked really well as you have heaps of space by your head/upper body and we both got a solid 4-5 hours sleep.