I've had the chance to use some of the new Citadel Washes that are coming out.
This is my review, part one:
I've not used the purple, red or flesh washes, but the green, browns and blue were really good and actually worked how GW has said they would. Suffice to say, I was shocked. I'm working on painting up Epidemius using many more of these washes. They really help to give him a sickly look off of the white undercoat. I painted up a reaper model as well using the washes to bring the model together. The Devlin Mud wash really works to make greens look like they are dirty and used.
Overall, with what I've done so far, I'm really happy with how the new washes work and will definitely be picking up a set when they come out, though I'll also be picking up a few choice inks, which I reccommend becaues those are being discontinued for the washes. And there are just some things that a wash cannot accomplish that the inks can.