I've had my 6600gt (AGP) for about a year and 3 months. It has been a great card. I play FarCry Single player with all settings on very high, AF on 16x (via the forceware control panel) and AA maxed out via ingame settings and 1024x768 at about 50 FPS average.
It also plays Doom 3 on high, Area 51 maxed out, BF2 at all medium settings with 2X AA with decent (40-50 FPS average depending on the map).
For it's time, I'd give it a 4. it wasn't the best card out there (6800gt and x850xt hold that title) but it was by far the best mid-range card. Nothing else could come close for the money.
Edit: I paid 139.99 After rebate from Newegg for mine. It's the Leadtek flavor, which I read was the best as far as cooling goes. Performance-wise they were all pretty much neck-in-neck.
I ended up putting the Zalman vf-700 alcu on it anyways after a year. It started to peak at 90C which is way too hot. After the Zalman, it's never gone above 60, and rarely peaks over 50