I wondered, too. Luckily, there's some hard data further down in the post:

[...] highly optimized, slim enough to fit the entire world onto a single USB stick.

Now that the exact size is known (1 world/stick), it's easy to get a feel for how this new format is better than the old alternatives, right? Grumble.

On a stick, the world (via OSM) is around 33GB. It's 300+GB in PostGIS, so about a 10x win.

Thanks! That really should have been in the post, glad to finally get some closure.

Thats pretty awesome!