Regular iPhone user here! I regularly use Facebook, Twitter (through the Echophone app), Pinterest, Weather Channel, my credit union's app, YouTube, Bible (FANTASTIC!), Feedly (for reading blogs), Instagram, GoodReads, Lose It, OverDrive (for ebooks, audio books, etc. from the library), Spider Solitaire, and Jean and I recently started playing Candy Crush Saga. All of these are free.
Enjoy your new toy!
M