I used Mig pigments for the first time on my revel U-boat and found them to be very effective. Have a look at the build thread here:
http://www.scale-models.co.uk/showthread.php?t=2410 (Revell 1/72nd Type VII U-Boat.)
I also mixed them with water and a tiny drop of washing up liquid to break down the surface tension and I couldn't beleive how good it looked when I wiped the excess away with a paper towel. They even gave a good effect for raised panel lines when I always thought that washes were only of use for scribed detail.
I am sure the Tamiya ones will be just as effective and a quality product. I will certainly be using them on all my models from now on.
I did a bit of reading up first and discovered that you can basically mix the powder with just about anything your imagine can come up with to acheive the effect you are after, from clear varnishes to resins to glues and all points in between. The possibilities are endless, as they say!