Alright, so, first things first. Despite the listed price, it's also 3lbs. So I ended up paying around $40 after S&H for the tester kit.
On the other hand, it's 3lbs of epoxy putty. That's almost 14 times the amount you get in a tube of greenstuff (3.5oz). Just in case you think it's just heavier. The tester kit for this stuff is a full pint of A/B.
The shore hardness for Freeform SCULPT is 80 vs Greenstuff's 60 and Brownstuff's 80 so it will harden to about the consistency of Greenstuff's tougher brother.
Probably the most disappointing thing though is that right out of the pot it's a lot softer than mixed greenstuff. It's about the consistency of wet clay, and seems to be water soluble as it left a watery residue on my wet fingers and tools. I'm not noticing any problems adhering to a surface though, in fact it kept sticking to my tools even when I switched from water to mineral oil.
Roughly an hour later it's the consistency of Greenstuff, but holds details and shape better.
Don't know if I'd recommend it for full mini sculpts as I don't do them much anymore, but for a lot of the much larger work I'm doing lately it's an improvement over GS economically and seems to be equivalent to that sculpting mainstay.