Inadequate range and cargo capacity compared to its' main competitor, the A330-200. With only about 5200nm range compared to the A332's 6400nm and a narrower cross-section limiting its below deck payload, this aircraft just doesn't appeal to enough operators. It was ideal for Continental's and Delta's domestic routes, replacing similar-range trijets but doesn't have the legs for most transoceanic runs. Boeing really needed to have the -ERX version with more powerful engines and fuel capacity to bring it back to 763 range but that version's engines were tied to the aborted 747X development so it was cancelled, as well. The smaller 170' wingspan also hurts compared to the A332's more substantial span. In designing it too much to be a domestic DC-10/L-1011 replacement, Boeing crippled it's chances with most carriers who wanted more. Saleswise, so far, I'd have to say that, yes, it's a failure, at least compared to the A332. A case of too little, too late for Boeing. Delta and Continental are very happy with theirs, if that's any consolation.