Looks like an interesting product, but I don't have any experience with it. Just from my reading, it sounds like it's not the best material for folks who want tough durability, or a pristine surface. Reviews mention it's very porous, so stains and dings/chips have to be viewed as part of the living patina of the surface.

I found lots of company mentions on the web, but for some reason it's hard to find any first hand reviews online, from folks who have used it in their homes. So, perhaps not widely used?

Here's a GW thread a few years old, with folks discussing Squak Mountain and two similar recycled paper countertop products.
Experience with Nucrete, Earthcrete, or Squak Mountain?

A product review, which even mentions how it smells (like Play-doh!) and lists some things you can seal it with:
Squak Mountain Stone

This site has a short review of it, in comparison to other eco-friendly countertops (not too positive because of durability concerns)
7 Eco Friendly Countertops Investigated

This Ikea thread has a brief mention, second-hand info from a carpenter, who said she would not use it because it's very porous:
Eco Friendly Countertop Options

I love the look of countertops like this (regular concrete too) but I think the maintenance and durability questions may reduce the popularity somewhat, since it's not inexpensive.

Fun to research, though...! I hope somebody turns up with personal experience.