I passed 70-642 with a solid 925/1000, I did not find the material specifically challenging but I am glad I had my previous experience with the CISSP. I don’t think I have any problems in how the material for 70-642 is presented in the self study kit, I just wish it had more depth in the technical aspects of the protocols involved in networking.
Personally with my own path I have taken, I found that understanding the protocols and functionality leads to understanding the configuration of devices involved. Looking at VPN or routing issues in environments with devices that you could have no experience on, you are able quickly identify the problem and the solution. The step in-between the problem and the solution is going to specific to the devices involved, once you know what needs to be done the fix is that much faster to implement.