I have been using an iSee case ever since iFriday. Was hoping that there would be a Showcase released for the iPhone. I have used Showcases and Vaja cases with every iPod I have owned and have been very happy with them all. Wasn't aware the Showcase was already here until I saw your post.
I am happy with the iSee with one minor exception. The only problem I have found with the iSee is that dust from your pocket does eventually work its way underneath the case. Not a HUGE problem.....but I do take the case off and wash it in a mild dishsoap-and-water solution roughly once a week. This is pretty much necessary to remove skin oil as well. So, no big deal.
I suspect this will also be the case with the Showcases just because of the big gaping hole required to allow access to the touch screen. Therefore....is it really a problem, or just the nature of the beast? You decide.
.....sT