Well, it's essentially taking the concept of
spaced armour and turning two layers with a single cavity into a honeycomb of multiple cavities.
A very nice idea and a sensible application of increasing complexity. The problem (if there is one) will be the manufacturing cost
HEAT projectiles are likely to prove fairly susceptible to this design, because spaced armour is already one of the best purely material defences as once the plasma jet starts coming apart it dissipates force quite quickly.
I'm not entirely sure of the mechanics, but I'd think the honeycomb as suggested should have a degree of elasticity that a solid block wouldn't, which would suggest a HESH-style spalling-inducing warhead would be less effective too.
Suitably high-velocity purely kinetic penetrators like APFSDS, on the other hand, will probably do rather better provided they don't disintegrate - a cavity of a similar size to the penetrator won't cause much in the way of deflection - and since they're designed to go through the same volume of solid material, the odds are in their favour.