Here are a couple of cards I made over the weekend using Paper Soft. I found it relatively easy to use (after a little practice) with cut & dry foam, and with a foam brush - covers the cardstock well, blends nicely and does not take too long to dry. You can apply it very lightly or more heavily for a deeper or more intense colour. Because it goes on very sparingly, it is not too 'wet' and so does not really cockle the paper like most paints would do.
On the first card I used cobalt blue and magenta, both for the background and I also applied it with a small sponge to the diamonds stamp. This worked well, although I wouldn't use it for a very detailed stamp.
The owl card has a background of cobalt blue Paper Soft which I applied onto cream card - this has given it a more 'turquoise' result. I then over stamped it with a leaf stamp with the same colour PSoft. The oval was embossed using Tim Holtz's woodgrain embossing folder, and then coloured with walnut brown Paper Soft.