Well the iPhone Buzz crew thoroughly tested out the ClearBoost iPhone case and found that yes, it did work, as long as they actually held the handset against their heads when making calls. If they used a Bluetooth headset, the case seemed to have the exact opposite effect, reducing the signal strength by about as much as it improved it otherwise.
So, if you have sufficient coverage or use a Bluetooth headset with your iPhone regularly, this case isn’t really for you. However if you have low signal, minimal coverage, and you hold your phone like people did in the good old days, this case couldn’t hurt as it did offer up fairly significant increases.
As far as it just being an iPhone case, it’s a decent hard case, but could use some padding in the back half to keep the back of the iPhone from getting scratched, but the screen cover was a nice addition. So, for $29.99 it’s worth it if it will do you some good, otherwise there are better looking cases out there.