I really like them, but there is a bit of a learning curve. The paints airbrush very well, but you do have to apply very light coats and built up the color. I use their thinner and mix about 75% paint to 25% thinner, then airbrush around 16-18psi. I have also used it straight out of the bottle at about 20-25psi, but again thin coats. Now the good thing about the thin coats is you can pre-shade, and it works out well.
Also, it does take a little longer then the standard acrylic to dry. I tend to let it dry overnight before masking, or give it a couple of hours before free-handing another color(camouflage) over it. I must say Ammo by Mig airbrushes a lot better then Vallejo Air, but I still prefer Tamiya, just hate mixing, so I tend to lean on Ammo when I can get it.
I am really pleased with them, my only issue is the lack of availability in Canada.
Hope that helps