The final step before using your new iPhone is to decide whether you want to enable Find My iPhone.
This free service from Apple allows you to use the iPhone's GPS features (you need to have enabled Location Services in step 3 to use it) to track the location of a lost or stolen iPhone. This isn't a required feature, but if you ever have your phone stolen, Find My iPhone will be a big help in trying to get it back. I definitely recommend using it.
Once you've made your choice, you're done! Your iPhone now has your apps, data, and settings and is ready for you to use. Enjoy.