Keeping track of your Bitcoins and their value should be simple.
Mynt is an awesome and beautiful little bitcoin tracker app that helps you with just that. Enter how many Bitcoins you've got or add a Bitcoin address and Mynt will keep track of it and give you the total value in any given currency.
Mynt uses background fetching in iOS 7 to get rates and address balances whenever possible. Everything to give you the current value as quickly as possible.