Having a dedicated number row on the Galaxy S5's keyboard is one heck of a time-saver. It makes entering passwords and phone numbers so much easier and faster. I can see why Apple hasn't yet embraced this perk, though; the iPhone's display is too small. But if the iPhone 6 is 4.7 inches or bigger, as it's expected to be, there's no reason not to let folks access those digits without having to press a separate 123 button.
Another handy feature on the S5 is next-word prediction. As you type, the keyboard tries to guess what you're going to type next. Samsung worked with SwiftKey to offer this feature, which gets smarter the more you use it.