The touch-screen is exceptional, close to the accuracy I've seen with the iPhone (but no multitouch) and vastly superior to the touch-screens I've tested on Windows Mobile-based HTC phones such as the AT&T Tilt. As with the iPhone, the screen is designed to be manipulated with a finger rather than with a stylus. I could easily place a call using the on-screen dialer, start applications and configure settings via the touch-screen, and I could easily scroll through long documents or Web pages with a flick of the finger. When needed, on-screen buttons to zoom in and out of documents are readily accessible and obviously placed, making it simpler to customize the view than I've found with the iPhone's pinch and spread gestures. When viewed in the standard portrait mode, the device has relatively few buttons. The lower portion of the front panel features six interactive controls-separate buttons for menu, call, hang-up/power-off, home, and return-to-last-as well as a trackball that can be used by those who don't want to use touch-screens to navigate and select items on-screen. These buttons will illuminate slightly when the device is in use to aid navigation in a dark environment.Unlike the iPhone, the G1 does not natively offer an on-screen virtual keyboard. Instead, to type on the device, the user rotates the device 90 degrees and slides to the screen up along a slightly circuitous route to reveal a full QWERTY keyboard. The slider has a nice snap that makes me worry about the slider mechanism's fragility over an extended period of time. Although the G1 has accelometers to adjust the display according to device orientation, the trigger to change the screen from portrait to landscape mode and back is exposing the keyboard, not rotating the device (like with the iPhone).The G1 keypad is among my favorites that I've typed on, with the keys widely spaced in five rows for accurate and relatively fast typing. The physical buttons and trackball used in portrait mode are also easily accessible when the device is in landscape mode. Unfortunately, the auto-correcting spell-checking tool the G1 purports to have never corrected anything for me when texting or e-mailing, although the automatic capitalization and punctuation tools worked as expected. There are but a few buttons or slots marring the edges of the G1. The left side of the device features a pair of volume buttons near the top and a covered MicroSD slot near the bottom. The G1 comes with a 1GB MicroSD card preinstalled, but the user can up the storage capacity. I found the G1 worked as expected with a 6GB MicroSD card, and T-Mobile claims the G1 supports cards up to 8GB. The bottom edge has only the covered slot of the USB connector, which is used as the primary connector for power, data cables and the wired headset. Like most other HTC devices, the G1 USB port has a USB-EXT connector. Although it is shaped slightly differently than the MicroUSB or MiniUSB connectors found on most portable devices, I could use the same data cable that I use for many other devices. However, because there is no separate headset jack, users who prefer a cabled headset have a limited number of options. The G1 package comes with a cabled headset that features an action button as well as volume controls, but I found the earbuds too large to fit comfortably in my ears. Users have the option of buying separately a comically large adapter (for instance, this) to work with existing headsets or headphones.