Viewfinder (0.0)
The Optio S5z has no optical viewfinder. This should not be viewed as a particular disadvantage; the S5z’s LCD provides an accurate viewfinder that's easy to see. Kodak puts viewfinders on many of its small cameras, such as the EasyShare Z700 and the C360, but they're terribly inaccurate and too small to use conveniently.
LCD Screen (7.5)
The Optio S5z has a 2.5-inch LCD screen with 110,000 pixels. Most 2.5-inch displays have at least 115,000 pixels, so in terms of screen quality, the Optio S5z falls short of its competition. Some point-and-shoot models today are equipped with nearly twice that much, such as the Sony Cyber-shot DSC-T1, which utilizes 211,000 pixels to form images on its LCD. The additional resolution offers a significant advantage to users who rely on the LCD to focus and compose images. However, for those 
who use their compact cameras as digital photo albums, keeping favorite images in memory and showing them to friends on the LCD, the display on the Optio S5z should be adequate.
One way to compensate for the LCD's low resolution when attempting to gauge focus is to magnify the image as much as possible. Though it shows a very small part of the image, a magnified view can be very telling. Unfortunately, the Optio S5z only magnifies onscreen images up to 8x, which is not as much as some competing cameras. The Casio EX-Z57 magnifies up to 12x, for instance.
Flash (5.5)
The Optio S5z’s flash has all the drawbacks that are common to small, built-in flashes. The flash unit fixed to the S5z is relatively weak, effective to only 11 feet at the wide angle end of the zoom range and 7 feet at the telephoto setting.
I can cover the Optio S5z's flash with my fingernail, which means it's an awfully small light source. That's exactly the wrong sort of light for taking flattering pictures of friends and family. As light sources get bigger, they get softer and more flattering. Wrinkles go away, and even discolorations tend to fade. Conversely, as a light source gets smaller, it becomes harsher. The Optio S5z's flash is just the right size to record every clogged pore on Cousin Joe-Bob's forehead.
Furthermore, the positioning of the flash will be troublesome. Pentax put the Optio S5z's flash well off to the right of the lens, rather than directly above it. This will result in distracting shadows cast to the left of the subject.
The Optio S5z offers several flash modes, which are directly controllable via the left button on the four-way controller. The modes are: Auto, which allows the camera to control whether the flash fires; Off, which doesn't allow the flash to fire; On, which forces the flash to fire; Auto Red-Eye, which turns on the red-eye reduction pre-flash; and On Red-Eye, which forces the flash to fire, with the red-eye pre-flash.
As most compact cameras do, the Optio S5z addresses red-eye with pre-flashes. You press the shutter, and the flash goes off three times, twice to make the subjects' pupils shrink, and then again a second later to take the picture. The drawbacks of the pre-flash system are twofold (at least): there is at least a one-second delay between the moment you press the shutter, and the moment the picture is taken; and the flash goes off more than once, which inevitably adds to the annoyance of the subject. With red-eye reduction on, the delay is about a second.
Zoom Lens (6.0)
The Optio S5z sports a 5.8 to 17.4mm zoom, which offers a slight wide angle to a mild telephoto range. A comparable lens on a 35mm camera would range from about 35mm to 105mm. At the wide angle end, it's wide enough to take pictures of small groups of people even in relatively small rooms, but not wide enough to document cramped spaces – you won't get the whole tub enclosure in the shot that immortalizes your bathroom renovation. At the telephoto end, it's long enough for portraits from about six feet away, but too short for getting shots of stage productions or sporting events.
The maximum aperture ranges from f/2.6 at 5.8mm to f/4.4 at 17.4mm. The minimum apertures range from f/4.6 to f/7.7 over the zoom range. Such small lenses can't perform well at apertures much below f/8.
