I don't think Google has a motivation to allow ad blocking, since ads are their primary source of revenue that fund other ventures (like chrome...)
The javascript rendering is insanely fast (Gmail, slashdot, digg, other sites that are "web apps", etc.). I think that it will give both Microsoft and Mozilla healthy competition.
I don't think Chrome is an amazing browser. But it does bring several things to the table that will make MS work harder on IE and give Mozilla inspiration too (each tab in its own process so if one page has a flash player crash, the browser can remain on, javascript speed, etc.).
For those of you who don't know, the Internet Explorer team was barebones and assigned to other divisions from 2001-2006 (espeically the office), with minor work for IE6SP1. The team was brought back together to code iE7. They sent cakes to Mozilla for launching FF2 and FF3 because Firefox gave them their jobs back