A couple of weeks back I sat the VMware VCP6-NV exam and passed with a really great score.
I have experience deploying and administering cross-vCenter NSX in production environments and found the exam quite straight forward, maybe 5 questions that I had no idea about but I must have got most ofthose correct as my final score was 481/500.
Advice I can offer if you’re looking to take this exam is use the VMware NSX Hands on Labs, read the NSX Installation Guide, the NSX Deployment Guide, the NSX Administration Guide and lastly for a really great understanding read the NSX Solutions Guide for Service Providers.
Also for some additional information you can look at the NSX bits in the VMware Validated Design documents.
Make sure you understand the components that make up NSX, where they sit in the architecture, VXLANs, transport zones, logical switching, distributed routing, edge gateways and very importantly how a packet is built and moves around in this new architecture than spans between the overlay (VXLAN) and the underlay (VLAN).
My next goal which I am currently working on is the VCIX6-NV advanced certification which I am hoping to create a study guide for each section of the blueprint.
Good Luck!
Musings from a past life 