The base layer of the midsole is a firmer Peba based layer of foam. It adds the structure into the midsole set up, which with the top 2 layers is a key feature. Without this layer, the shoe would probably be unstable. With this base layer, it provides some structure but it is still not a stability shoe. It is Neutral Funtastic.
The middle layer is a "Super Boom Capsule", which basically acts as a spring mechanism underfoot. You will hear other runners say "trampoline", "Jelly Rebound" and "explosive Pop", I tend to use pogo Stick bounce.
The Top layer is a soft plush layer of foam, similar to the softer type of race foams.
The combination with the geometry/forefoot rocker is an absolute joy to run in....and walk in for that matter. This is a shoe that gives back to you and then some. On my 15 and 20 mile runs, the shoe never lost it's energy on the run and felt like it was bouncing me along. It actually seems to give back as good at faster paces without any flattening out that I can experience with some other high stack shoes, it maintains the energy return.
If you like ground feel, this isn't a shoe for you.........but then if you are looking at this shoe you probably already know that. It can be a little unstable. I wouldn't use this for an obstacle course, but that is again something most runners looking at this shoe would be aware of. I will say for the amount of stack, I felt fairly nimble in the shoe. I felt more unstable in the Neo Zen OG on corners, this is more stable than that shoe from my experience.
There are times on my runs when my legs get tired and I hit an incline during a walk. I tend to run up the incline to enhance the effort, but those first 2 strides are normally "ugh" moments. In this shoe, that ugh disappeared on first contact as the shoe just bounced me into rhythm. I just can't say enough about the fun of running in this shoe.
As noted before, I would label this as Neutral Funtastic type of shoe.