There are many other factors affecting the performance of a digital camera that are more important than sheer megapixel-power. The first and most important is the quality of the lens. It's hard to judge the optical quality of a lens without seeing sample shots taken using it, which is the main reason that we now started provide full-sized samples with our reviews. Things to look out for are barrel distortion at wide angle, as well as blurring and chromatic aberration around the edges of the frame. However there is one factor of lens performance that is usually printed right on the front of it.
The maximum aperture range, or "speed" of the lens describes how good the lens is at capturing light. If you look on the front of the camera, often printed around the front of the lens you'll see a series of numbers, something along the lines of "1:3.2-5.3" or "f/2.8-f/4.7" or something similar. If it's not there it will be in the manual, and it's well worth looking up. This is the range of maximum apertures at the wide-angle and the telephoto ends of the zoom range, and ideally you want both numbers to be as low as possible. A low number means a wide maximum aperture, which means the camera can use faster shutter speeds in lower light conditions, which will produce steadier, sharper photos. High-powered zoom lenses often have slow maximum apertures at the telephoto end, which can make them difficult to control in all but the brightest sunlight.
The inner workings
Also vitally important to camera performance is the quality of the electronics and software that turn what the sensor sees into the finished colour photograph that you see. The best manufacturers are constantly striving to improve their image processors to speed up performance, improve colour rendition and exposure, and to reduce image noise at high ISO settings. Again this is something that you can only learn about by reading reviews or by trying the camera yourself before you put down the cash. Turn it on and see how fast it starts up, take a picture with it and see how quickly it is ready to take another one, and then turn the ISO setting up a few stops, take a picture and zoom in on it to see how much image noise you can see.