I have had good and very, very bad experiences with it. I've hatched 3 clutches on it so far, but I've lost about 4 clutches total now trying to use it.
As mentioned above, the problem is the 6,7, 10 months it takes for chams to hatch. When you go to reapply water when it looks like it needs it, you realize 'HOLY s*** IT'S ALL DRY' when you think it's just the surface that is dry.....and then you add too much and BAM you've got water drowning your embryos.
It's easy to get going to begin with, but reapplying water when you have eggs on top of the Repashy is tricky and risky business. After about 3 months it looks fine (moisture wise), but after 4-5 months it dries up quick, leaving your eggs in bone-dry conditions if you don't 'catch' it at that right moment when it gets dry, and don't add too much water.
It's awesome for geckos, but chams no way. I am now using more conventional methods.