I think the thumb layout is more comfortable and easier to use.

Kinesis users I've put in front of my prototypes come up to speed pretty quickly.

Non-kinesis users seem to come up to speed a lot faster than they do when confronted with the kinesis' bowls.

Also, it's a lot more portable.

And it's really, really fully programmable.

I have a Kinesis, and the trouble I found with these were that they are raised too far above the table surface which causes neck strain for me. I have had better luck with the Truly Ergonomic but this looks even better!