@lisreed. I have had one of these about a week now, I love it. I was hoping it wouldn't be a flimsy, cheap sort of plastic --it's not, its thick (but not so thick as to be distracting) and also strong. I love the 'feel' it gives the Kindle, it was a very satisfying feeling hear the audible 'clicks' as this case snapped into place, sort of like I was strapping battle armor onto it. It fits perfect too, you honestly can't slide a piece of paper between the plastic and the Kindle, its that form-fitted -- so I don't know how that would affect the fit of a Kindle + Skin inside this case.
I had bought it as the same time I bought this:
http://www.amazon.com/gp/product/B0025LP6OM and they arrived the same day, but I was really unhappy with the TrendyDigital case. The leather sleeve that held the kindle was misaligned, so the cutouts didn't match the Kindle as well as I would expect. So I went Frakenstein on it and cut out the leather sleeve, and what do you know, the outer leather 'shell' of the Trendy makes a perfect snap-wrap for the plastic case!
It isn't a 'reading' case, you won't hold this like a book since it has no clips or straps inside anymore. This mod is more of a travel wrap for protection in a purse or bag (I had bought this Kindle for my mom to carry to work with her, so I know it is going to be safe now). Sorry for hijacking your thread Lis, just wanted to toss this idea out there and let you know what I thought about that plastic case you got, hope you don't mind! =)