How is your experience going with your 4S? Is it lacking at all, and how? Do you need the larger screen size of the 5 to make your experience more fulfilling? I've been debating making the upgrade from my 4S to the 5, and despite occasional shifts, I've mostly decided to wait until the next iPhone release.
Here are some possible reasons why: 1. If I upgrade now I will wish I would have waited until the next iPhone came out**. 2. Like you, I love my 4S and find it in no way lacking. 3. By the time the 5S* comes out the line of accessories will be more filled out and refined. 3a. I'm invested in and dependent on my current accessories that aren't matched by the current level for the 5. 4. The 5S* is going to be even more awesome, and if I get the 5 now I won't be able to upgrade until the 6**.
*Assuming Apple names the next iPhone 5S
** This is ignoring the fact that i am likely able to sell my current device and be able to fund the upgrade.