To be fair the second display does exactly what it says on the tin. It does make it easier to frame self-portraits and self-timer shots, and the clearly visible countdown in self timer mode means that everyone knows when to say “cheese”. If you frequently find yourself taking that kind of shot then there's no question that it is a useful feature, but is it useful enough to pay extra for it? The ST500 is currently selling for around £170, which is a lot of money for what is otherwise a fairly unremarkable compact camera.
It does offer a couple of other nice features though. It has a decent 4.6x zoom Schneider Kreuznach branded lens with optical image stabilisation and a 27-124mm equivalent zoom range. It also has a good video recording mode, shooting at 1280 x 720 resolution and 30fps. The optical zoom can be used while recording, but unusually the camera mutes sound recording while the lens moves. Personally I'd rather have a bit of motor noise on the soundtrack than big silent gaps, but maybe that's just me being odd.
The touch-screen interface on the ST500 is a prime example of why I don't think touch-screens are a particularly good idea on cameras. On a phone, where the interface is the main purpose of the screen, they're fine. Phones tend to have bigger screens than cameras anyway, so they can have nice big buttons that are quick and easy to use. On a camera the main purpose of the monitor is for framing shots and viewing images, which means that the touch-screen elements have to be either very small or hidden away most of the time, or in this case both. The screen of the ST500 is also pressure-sensitive rather than the finger-only capacitance-sensitive screens used on most phones. The sensing layer is slightly silvered producing nasty glare when used in sunlight.
As well as the touch screen, the ST500 has an accelerometer, allowing a limited degree of “gesture” control. Oh, and it has “haptic feedback” too. The cameras buzzes slightly when you touch an on-screen button.
Other than the gimmick features of dual screen and touch interface the ST500 is a fairly average camera. It has the usual selection of program auto, full auto, “smart” auto and scene mode, with 13 scene programs. It has adjustable contrast, saturation and sharpness, but not much else in the way of creative image control.
The ST500 is the second recent Samsung camera that I've seen which uses MicroSD cards for storage. These are the tiny memory cards normally used in mobile phones. They are a little more expensive than regular SD cards and are a lot easier to lose. Of course they are also much easier to swallow if you're captured by enemy agents, although off the top of my head I can't think of any other advantages.