it's hard to say a whole series is a failure or not....
fx5200 with 64bit memory bus (or pci version) = failure
fx5700u = winnar
fx5800u = winnar if you like noise
fx5900xt/le = winnar, these babies overclock quite nicely
fx5900u = loosar
fx5950u = despirate attempt to make previous loosar into winar, one in which failed
ah, you win some you loose some IMO. the only reason i say the fx5900u and the fx5950u's were failures is not because so much of performance, but the price of them was just completely outragous. even when the 6800's came out the prices were still over $350, that's just obsurd.