I use the factory shipped cyan rubber case too, but i like SO MUCH how the phone looks and feel without it, just love the curve screen, but it's more slippery and you must handle it more carefully. Almost 98% of the time it's inside the case. I've taked it out three times to play with it.

In the next days i'll be ordering the CP-553 leather case. It's simple; do you like the "nude" N9? Then take it out from the case, enjoy it, and when you finished simply slide it into the case again and you're done, and the screen also gets protection!