The iPhone 6 series smartphones feature phase detection autofocus. This is the autofocus technology found in DSLRs. And that means focusing will be fast. Here’s a good primer on how phase detection autofocus works.
The iPhone 6 has digital image stabilization while the iPhone 6 Plus has optical image stabilization. Optical is better than digital.
For selfie lovers: burst selfies and single-shot HDR selfies.