The one place it's lacking on the iPhone is in text selection--because there is a Shift key only on the left hand side of the keyboard (instead of both sides as it is on the iPad) it makes selecting text to the left of the cursor slightly more difficult. (It works best if you hold Shift with one finger, and swipe left with another.) Other than that, though: GENIUS.
EDIT: I actually did stumble onto something that could end up being a deal breaker for me. I can no longer use the swipe method of typing numbers--where you tap and hold the number key, slide to the number, and release to return to the letter keyboard. My guess is that I use that feature far too often to lose it.