Just got the Agent18 Video Shield for my 30 Gig iPod Video. I had it pre-ordered and then shipped 2nd Day Air.
For a brief review, I'll say that I am impressed so far. The quality seems high. The majority of the case is frosted, with the exception of the area covering the screen and a small window in the back that reveals the Apple logo.

The frosting makes the black look a little silvery, which I enjoy. It snaps together easily and securely.
My fiancee joked that I was performing surgery to put it on. I'm very serious about things of this nature, so I had the iPod laid out on a microfiber cloth while I gave it and the case a good going over with some iKlear. Once streak and spot free, I popped it into the case. It fits very well, and slides into the front half with enough resistance to let you know that it's a good fit, but not so much that you feel you might damage it.
If there's any interest or concern, I may be able to take and post a picture or two. So far, my only concern is a small white line running from the top center of the clickwheel to the bottom of the screen. Looks like something to do with the molding process. It doesn't affect function in the least, but is perhaps a minor cosmetic flaw.
I also have not had the chance to drop it to test protectiveness, and with all due respect, I'm not about to throw my iPod down the stairs, even for you kind people.

So far, I'd give it a strong A!