I know the Samsung Galaxy Nexus is not the newest phone, but I believe it's still one of the best devices out there. Stock Android from Google! And it's Samsung. Quality. Anyway, about the Diztronic case: I put some research in it before purchasing, and now have been using it for almost a year.
It's matte black. It's some non-rigid, flexible material. It's not a gel case though, but somewhere in between. Not too soft, not too rigid. The surface is not too slippery due to the matte finish, so when you hold it, it won't slide out of your hands too easily. On the other hand, since it's a somewhat hard surface you won't have any issues with slipping it into your pockets and pulling it out.
The top side is shiny, and grips the edge of the screen from the front. This goes well with the shiny surface of the screen itself, and since it protrudes further than the screen, it protects the screen as well in case you drop the phone or put it down with the screen facing downwards.
All the holes for the control buttons, the camera, the microphones etc. are precisely in place. The case does not hang away from the body of the phone anywhere, but holds the phone tightly. Yet, it's still easy to remove the case or put it back on.
The case is not too bulky, but thick enough to protect your phone in case you drop it, as I did a couple of times.
If you like the colour, and you ask me, this is simply the best case you can get! I can't find any faults in it.