I've gotten the " your device will be shipped this week" email, but I've already got my case. http://www.amazon.com/dp/B00A823OAI/ref=pe_175190_21431760_3p_M3T1_ST1_dp_1 and to be safe, I've been constantly checking the ghost amour site and they finally have the amour for the N4 but only in clear which is fine. I know ghost amour is a fully body protector and a case might be overkill but that's just my OCD. I've waited for to long for this phone and to mess it up now would drive me insane.
I'm currently using a Seidio Active--it's a softer otter box clone with a kickstand. It provides decent enough protection but adds way too much bulk and kills off the lovely curved edges of the screen. I'm using this because I'm trying to decide if I want to replace my ringke slim with another ringke slim or get something else. The slim definitely does a better job at showing off the phone and has better "hand-feel".
I would recommend the slim to strangers on the Internet. Most of the time people who used my phone with it didn't even realize I had a case on it. Even helped my phone survive a drop on concrete at a baseball game.