I didn't even know the existing ones didn't!
Same here! Their example page does show some slight differences, though.
Ah yeah, just checked out the samples. Not bad!
In Chrome Mac the main differences seem to be the use of ligatures and better kerning. I'm wondering if that's enough to switch away from Google Web Fonts… What are the downsides?
I've got a sharp eye, but at 300k for Brick, vs 92k for Google Fonts, I've got to go with Google Fonts here, especially when I'll usually have a given Google Font cached anyways, so it's often 0.
Note that the 300KB is probably the maximum size of all the fonts in the catalogue. I'm using EB Garamond in the previews, which is one of the largest fonts in terms of size.
If you're on a Mac (I'd assume most people here are), all fonts are rendered pretty well.
But on Chrome in Windows: http://imgur.com/a/QVIho
Note: That's not my screenshot, someone else kindly shared it.