I have been using Otterbox cases for my Blackberry ever since I got my very first device. This is my 3rd Blackberry case now and my 4th Otterbox case (I got one for an PDA I used to have). They were all Defender cases and they all worked like bosses.
This case I find is no different. It protects the phone very well. Yes you do get a little duct under the screen protector at times, I take mine apart every 2 weeks or so and clean up and that work just fine.
My one complaint about this case is the belt clip. The bottom has only one cradle in the center of the base, which means you have to line the phone up properly or it may go in on sided and fall out. Also, because it only has that one middle clip if you bump into something its very easy for the base of the phone to be pushed out of the case. And you know what happens next? Yeah it falls completely out of the case. I constantly have to check and make sure it's still there throughout the day.
The base of the new Q10 case is more like what I would like to see here. I plan on modifying to solve this problem, but it's going to make the clip look cheap, but hey I prefer that than to lose my phone.
Maybe it's time for an Armour case for the Z10?
All in all a great case, just need to do something about the belt clip.