Now you start talking about their cpu's. There is nothing fundamentally wrong with them. They are low performance and so are comparable solutions from the competitors (good luck doing image editing on an atom). Low power CPU's are not meant to do this kind of jobs. It could be arguable whether their performance/watt ratio on the cpu is still so competitive, but this thread was about their GPU's, so lets not get into that.
BTW Svartalf, clock-by-clock PIII was much better than PIV (Netburst was designed to be high clock and low performance per clock; it was a marketing move, remember?).
There is that...
However, it should be observed that they didn't do QUITE as well as the PIII Celerons at the same clocking. Their original main claim to fame was roughly 1/2-2/3rds the integer performance of a comparable PIII Celeron with vastly less power consumption- while all the other low-power solutions were in the 486 classes of performance.
People kept looking for miracles out of the things, even VIA, if you want the truth of it. The Nano's the first one that might be close to living up to their hype on the part.