I bought this product minus the "pen." The little bottle tip with the rubber cap dries out, and I always have to stick a pin in it to get it flowing. I use it mainly for glueing intersections, and it works well for that... but I can do the same thing with Elmers Washable School Glue for less cost. The Elmers glue comes apart for pressing seams open just as well as this product as long as I don't use too big of a glob of the Elmers.
I like to press my seams open, and if I get a seam that doesn't want to lay flat, I'll put a few dabs of this product on the inside of the seam, iron it dry, and problem solved.
It's a nice product, but I'm comfortable with using Elmers for the same thing so I don't think I'll buy it again.