Most of the threads that mention P3 paints are part of threads about the GW foundation paints.
If you do a Search of Foundation paints you should find about 3 threads.
As for the P3 paints themselves, I picked up three of the 6 packs about 4 weeks back and I love them. I plan on picking up a complete set as they are released.
The increased pigmentation is amazing and really does allow you to coat quicker without ubscuring details.
I know it\'s a no-no by profesional painters, but I find they also work great our of the pot, not requiring much watering down.
When you do water them down they flow better then any other paints I have used, leaving no \'rings\' when used as washes.
My one complaint about them so far though is the colour selection. It\'s a bit annoying to get both a base and a highlight for every colour. Sure it\'s quicker, but I find mixing highlights isn\'t something that takes very long. Plus I found the highlights not quite bright enough so I am still mixing for highlights, so really in the boxed sets at least you get some \'useless\' paints.
Compaired to the Foundation paints from GW I find these flow better and definately mix better with themselves and other paints. They don\'t coat quite as well as foundation, but they are still way up there on coverage.
There is a video on youtube you can see these demonstrated as well:
http://www.youtube.com/watch?v=QkkzU6GqNpg