The downside, however, is that shrinking a full-sized keyboard to fit your pocket means a few compromises. Here are a few pointers. Also, Qwerty layout is best. Having to relearn key positions is a real nuisance. Clear display in poor, artificial or outdoor light is crucial.
Some screens go black in bright sunlight, others dim to illegibility indoors.
Having a good backlight will help, but using it for more than 50 per cent of the time will cripple battery life. Being able to make text appear bigger is also a bonus. Look for a compromise between legibility, size and stability. In general, Windows-style menus don't work well on tiny screens, even in colour. Shortcut icons are easiest to use.