I am also on my first Nexus, the first piece of advice I could give you is to go in with no expectations. You are used to the TouchWiz UI and the Nexus is pure Android. There will be things you are looking for you will not be able to find on the device right away.
However if you go to the Play Store you will find many apps or substitutes which will work as well if not better and your phone will also be faster and cleaner. I am still in the discovery mode, but enjoying every minute of it. I get a little frustrated at times when I can't do exactly what I want and then it is time to start searching for the solution. It is out there!
Have fun on your journey and good luck!