These tiny keyboards are a challenge, every little bit of added facility helps. The Arrow Note keyboard (iPhone only
AFAIK) is cool, much better than anything I encountered on Android, though I only tried three: the stock, later with cursor arrows enabled in the settings menu, Swiftkey, and the Hacker's Keyboard. The Android apps with arrows were sort of a drag - they didn't have the swift movement if you hold down the key feature - had to tap, tap, tap and soon enough you'd miss and hit something else. Arrow note has that, the rapid movement I mean. It also has a comma key in the middle of the arrows bar that gives a comma and a space. Very handy, especially with the iPhone keyboard.
I think it's used now on the iPad. Why it's downloadable on the iPhone is a bit of a mystery to me as you can't use it on any normal composition page. I dig it because I like the voice to text business, works quite will but hard to edit with the touch cursor for me, especially on Android.