Acrylic cases are 100% gimik. Scratches and scuffs will show up on it like they have a spot light on them. Now, if you wanted to put a fish bowl into the computer, such as on top, it might be a decent option. Then again, you'll need to install some heat insulation material or you'll have fish soup instead of fish.
Personally, my case sits under my desk, so I don't see all of it. I see enough to know it's there, looks good (it makes black look gooood) and is running properly. I'd also like a case that I don't have to worry about cracking the area around the screws if I tighten them a bit too much. That can happen with acrylic, which will make it look like crap and be less stable/reliable.