The N9 is very slippery but I have an invisi shield on it which gives it so much grip and it feels good in your hands too. I use the OEM case most of the time but when I do take it out, I have the invisi shield all around it so no worries of getting scratches or anything at all.

If you don't want to get a case, I would suggest getting the invisi shield. I bought mine for $15 from eBay, so trying going that route maybe?