Luke Halliday of Capsule Computers writes:
"No. 6 is a series that had ton sof potential but was doomed to never live up to it. Weighing in at a mere 11 episodes, it was always going to be hard for BONES to adapt the epic scale portrayed in No. 6′s source material with such little time. In the end the result is a sloppy, awkwardly paced, relatively disappointing anime series albeit one with real heart underneath all its flaws. But is heart enough to make up for such apparent faults?"