PIP
If I'm not mistaken, the often mentioned performance shortcomings were addressed through the PIP - Performance Improvement Programs, and after PIP-Phase 3 seems the beast actually performed better than originally advertised.
Off course, this all came too late and the damage to the sales could not be undone.
I spent almost 4 years working with MD11s and the crew were all very enthusiastic about it. Respecting and knowing your ride is the keyword here.
BF