If you get bored of Touchwiz, go download nova prime launcher. Lots of cool ways to customize your phone with that. Gestures can be convenient (double tap screen to launch camera, swipe up to launch navigation, etc...) they are pretty clutch when driving and just make life easier for your most common uses.
Also recommend getting a premium case like the Spigen Neo Hybrid to make it look and feel a lot more premium. I know most converters aren't fond of the plastic cheap feel, so a nice case like that will add a lot to the overall look & feel.
I've had the iPhone 5 and it's just all personal preference. I enjoy the bigger screen (better brighter and more vibrant too), I like customizing everything (I jailbroke my iPhone to do this, and I really like the 13mp camera on the GS4).
http://i.imgur.com/7AFAxZpl.jpg?1