iPhone Duo review: the outer device is by far the worst iPhone Apple has ever made, while the inner device is a splendid tablet with a UI that bests the iPad's

If you want a phone, this device is a significant downgrade from any current iPhone.

The iPhone Duo, a new foldable device from Apple, presents a split user experience according to a review by John Gruber of Daring Fireball. The outer screen, when the device is folded, offers a "miserable fat little thing" of an iPhone experience, plagued by awkward pocketability, a cramped UI, and a return to Touch ID. Gruber asserts that Apple has not adequately solved the inherent compromises of foldable technology, particularly for the outer display, comparing it to a compromised Transformer toy. This folded state is described as significantly worse than any standard iPhone, including the less popular iPhone Mini models, due to its thickness, weight, and the unnatural placement of UI elements. The design also poses usability issues for left-handed users. Consequently, the outer device is deemed the "worst iPhone Apple has ever made."

The inner display, however, transforms the Duo into a "splendid, joyful, beautiful tablet" that Gruber ranks as his favorite tablet experience, surpassing iPads and Kindles. This inner screen boasts a UI that outperforms the iPad's, suggesting a potential new benchmark for tablet interfaces. The seamless transition to a large, lightweight tablet experience when unfolded highlights a significant achievement, positioning the Duo as a device that offers the best of both worlds, albeit with a stark trade-off in its phone functionality.

This dichotomy suggests Apple is exploring a new form factor that prioritizes tablet use over traditional smartphone convenience. The success of the inner display indicates a strong market for premium tablet experiences that remain highly portable. However, the severe compromises in the outer 'phone' mode suggest that foldable technology may still struggle to replace a dedicated smartphone for users who rely on frequent, quick interactions throughout the day.