There is no way a cellphone can kick out as much light as an actual table lamp such as these ones offered by Philips.
I set mine on 20 (the maximum allowable setting) so that it's as bright as possible when I want to wake up. It's bright enough as a bedside reading lamp and dimmable all the way down if you want to set the mood. This thing has now replaced both my traditional alarm clock AND my traditional bedside lamp in one appliance.
Note that when you flick on a traditional bedside lamp, it will come right on at full force and is a harsh transition from darkness. The Philips lamps fade in when you turn it on, so it doesn't hit you like a freight train. It turns off in the same way, powering down to give you a couple of seconds of fading light so you can adjust yourself in bed before pitch blackness.