Matte screens tends to looks slightly grainy to some people. This is due to the Anti-Glare (AG) coating on it and the purpose is not to reflect light back towards the viewer like a glossy screen. The grainy texture help diffuse the light into several directions so that the screen does not act as a mirror. Matte screens makes it easier to use a laptop/netbook in direct sunlight compared to glossy screens. Some matte screens have heavier AG coating than others. Some people say that when viewing a white background the AG coasting makes the screen look "dirty" because the AG coating makes it seems like there are tiny, tiny specs of dust on the screen.
Additionally, the LCD panel in the netbook can also be of low quality to help keep costs down and can be attributed to some of the image artifacts you are seeing.
In the end, there is no such thing as the perfect LCD screen. You must live with the limitations of glossy and matte. There are other things as well, but that's beyond the scope of this topic.