My babies aren't old enough to be laying just yet, but I love their temperaments! They're not as social, curious, and calm as my Mallard, but I suspect that that's because I got them when they were three days old and I didn't handle them nearly as much as I handled Pyrrhos. However, they are definitely a lot more calm that I expected, and very willing to take food from our hands. Out of our four Welsh Harlequins, only one was sexed incorrectly(by us, not the breeders).
Aside from their awesome temperaments, they are so beautiful. Even though we have three hens, all three are colored differently. We even - by chance - got a gold phase hen! (: That definitely makes me one happy duck owner haha.
As my ducks haven't started laying yet, I can't comment on their laying abilities or their broodiness, but it seems pretty much common knowledge that WHs lay excellently and are broody and great mothers. My ducks are all relatively calm and easy-going with our dogs. The only time they get uncomfortable is when someone is walking toward them and gets too close. None of them like to be pet or picked up, but they all are very willing to come up to us.
Overall, I have to say, I love these birds, and I'm excited to begin breeding them!