The Crystal GD900 is a slider whose numberpad's white markings glow against their tempered glass surrounds. After a moment, the glow subsides and you can see the numbers, but much more faintly. Touch the numberpad area and the white glow returns.
The keys are flat, and while I had no trouble working at a fair speed, ultra-speed texters may want to try before they buy to be sure that they can get their fingers flying fast enough error-free.
The transparent numberpad looks, to me anyway, rather cool, and there is no denying, even if you don't like it, that it is innovative. There are lots of touch control niceties here and on the screen. You can get through content such as photos by sweeping a finger horizontally across either the screen or the numberpad. Sweeping upwards opens an information screen telling you, for example, when a photo was taken, its resolution and file name.
You can pinch to zoom when viewing photos, emails, web pages or maps. This was fairly responsive. The first zoom in any photo took a short time to work, but thereafter zooming was smooth. Again, this works on either screen or numberpad.
Perhaps a bit more interesting is LG's Gesture Control, which is located on the numberpad, which, by the way, LG calls the Transparent Touchpad.
There are three shortcuts under the screen - Call, End and the LG ‘cube'. Press this for a second and the multitasking menu opens up. Here you can get to a subset of running apps. But you can also tap a button to set up the gesture shortcuts. There are 12 of these and you can assign them to nine different apps. So even when maxed out, three gestures will remain unused.
With the assigning done, simply tracing a shortcut on the Transparent Touchpad opens its associated app. These gesture shortcuts can't be used on the screen, so you have to go through up to three stages to make a shortcut work: slide out numberpad, make gesture, slide in numberpad. It is hardly a superquick option but it works, it is innovative and it can save time when you are in one app and want to switch relatively quickly to another.
LG again uses its S-class 3D user interface in the Crystal. This comprises four main screens you finger-sweep on either the screen or Transparent Touchpad to get through. Dedicated to favourite contacts, multimedia, shortcuts and widgets, all can be customised. Whichever of the four you are on, links to the main menu, phone dialler, contacts and messaging are always present on a strip along the bottom of the screen.