Even though I am not really a theme person, because I like to keep my system as light and fast as possible, out of curiosity, and because it looked nice in the web screenshots, I went ahead and downloaded Crystal Black.
I should have listened to the warning comments here instead.
Not only was I not impressed by this theme running on Lion -- it looks like something out of the 1990's and has jagged edges around some of the icons, and other issues -- but contrary to the developer's claims, even though I used the uninstaller to remove it from my system, and have since rebooted my iMac, there are STILL remnants of this theme on my machine, such as with the App Store app. Even relaunching the App Store app a few times does not remove Crystal Black from its menu bar.
I am not a happy camper.