Disappointed that there isn't any innovation wrt tabs; they aren't mentioned at all.

I understand Lightspeed aims to be minimalistic, but many of these defaults are just illogical. Default click-to-play at the moment already ruins many audio sites where the flash applet is hidden, and turns others into a game of Where's Waldo.

Completely dropping extensions is antithetical to the central idea as well. Ideally, the browser would be barebones and fast (what Firefox once was) and any features would be an addon. Otherwise, you get sucked into the mentality of "if only there was this one feature".

All in all, there seem to be several inconsistencies in the central idea, but it could definitely turn out to be an interesting idea.