Nintendo Life's Philip J Reed writes:
"Nano Assault is a gorgeous trip through the beautifully-rendered worlds of the human bloodstream. It's both punishingly difficult and endlessly satisfying, and it does an excellent job of keeping the action varied and the tensions high. The difficulty is bound to infuriate some potential customers, but the levels are fairly brief and can eventually be mastered. Apart from some small issues with slowdown and the frustrating tendency of enemies to spawn directly beneath you, Nano Assault is an easy recommendation for shmup fans, or anyone who really wants to see what their 3DS can do."