They have put up a video of the new system in use - TerrainLinx
All I could think of while watching it was 'Wow, just like Panel & Girder for fantasy!' (Not an insult, by the way - I loved Panel & Girder, and still have a set that I have used on occasion just for gaming.
The cardboard tabs might be a bit fiddly, but it looks pretty darned versatile. I like how it layers up, so you can build a sewer, put a street over it, then put buildings along the streets.
Most of my builds tend to be permanent, and this set is definitely aimed at terrain that is built, used, then torn back down again, though I can see how a bit of glue would fix that.
But really, what sold me was this picture:
It calls out to the Nosferatu in me.
I really want them to come out with a Victorian subway set to interconnect with the sewers. (Yeah, I know, it is more properly called the Underground, but most of us are Yanks, not Poms.
The Auld Grump