The 6600GT AGP is nearly the perfect 200$ board - it has massive amounts of power that rivals and in most cases exceeds the performance of the previous generation of top of the line cards. Remember that the 5950 and 9800XT were 500$ cards barely 8 months ago. For users that are currently on a 5700 or any card from the previous midrange generation, the 6600GT is the best upgrade path available at the 200$ price point. Classical game performance is excellent and the Directx 9 performance is no slouch either. One of the key selling points will likely be the DOOM 3 performance on this card which is simply phenomenal compared to the last generation. DOOM 3 performance should be an important purchasing factor as there will be a whole slew of games based upon its engine.
The only real downside to the 6600GT is the memory bandwidth as it is somewhat hampered when AA/AF is applied to the higher resolutions. In many cases, this point is merely academic as even the higher framerates offered by the 9800XT in those situations will not result in a pleasing game experience. AGP users that are not ready to shell out for a 6800 series card should not look any further than the 6600GT as it arguably has the best price/performance ratio out of any card in the 200$ range.