I'd say the higher end FX line 5900U, XT and 5950U were a failure in that they werent prepared for the next generation of games that use bump mapping and shaders like halo (that was released while FX5950U was gearing for release), far cry and bfv.
So forking out 600$ a year ago for a card that was basically out of date for these new games makes it a bit of failure. But the competition didnt do much better and you might also say those games were ahead of their time.
I went from Ti4200 -> FX5950U -> 6800GT and I get the same warm feeling from the 6800GT like I did from my Ti4200.. jaw dropping FPS, and worth every penny. And I got about half the price of the 6800GT out of selling my 5950 so it wasnt a total loss there either.
A64 3200+, MSI NX6800GT, Asus K8V SE D, *NEW* 2GB DDR400 (BF2 likey), 200GB WD Caviar, Nexus 4090 400W silent, ATC220B, Zalman Reserator 1, Innovatek CoolMatic NV40, NEC 3500AG, CM AerogateII black, Smart Drive 2002C | 20,1" 15ms TFT 1600x1200 Formac Gallery 2010 | Temps: idle CPU 45c GPU 55c, 1h+ gaming CPU 55c GPU 67c