I ordered / just received this one for my 8830 (it says it's for the 8800/8830). So far I'd have to say it's not that great for the 8830. It's fine unless you hold your BB by the sides. Then the case seems to "squish" in a bit and it's not tight anymore.
I'll have to use it for a day or two and then give more feedback.
This case makes the keyboard feel "thick" and it is VERY strange to type with the case on. Yes, the keyboard still functions with reasonable accuracy, but it doesn't feel even close to as sure as typing directly onto the BB keys. I went with the OEM rubber case and I like that the form and function of the phone remains intact, while the shock of placing the phone on a surface is considerably absorbed by the case. I'm really not sure why you would need the keyboard cover unless of course you are concerned about moisture entering the device through the keyboard...
The fit of the OEM rubber skin has perfect fitment and is very natural.