We spoke about this on the podcast, I think this is a solid step in the direction we'd want the Matoran to go, and I'm actually excited to get a kit working (if nothing else to replace that other Matoran template that people use for their OCs that I'm not a huge fan of).
It's great that they look more ancient and like "last year's model", it makes the Toa stand out that much more while making the Matoran still visually interesting without being pain. I originally didn't like the pistons, but really came around to them. It does bear that visual tribalpunk look that I felt was at the core of the Bionicle art aesthetic.
There's like some things I would tweak, but I think Ven and Var might be working on some kind of final finishing touches. I'd actually be super interested to see what @Ragdoll's take on a slightly revised design would be?
The only big thing I kind of have a "problem" with is the heads. I think they're a little too skeletal and lose out on the personality aspect that the Toa heads do. I would think that the heads would be extremely similar to the ones the Toa have. Specifically, the eyes and expression need to be a lot more prominent.
That being said, really good stuff.