Google's new Blog search is good - very good. And for very many reasons.
First off, it works very well and brings in relevant results quickly and without fuss. But Technorati and Feedster were already very good in that department.
What I really like about Google doing blog / feed searches is that it will make blogs even more mainstream. Everyone knows how to Google, but few non-nerds that I know are aware of Feedster or Technorati and the like. Once the blog search is fully integrated into the basic Google search experience, casual users will be able to discover blogs more easily and without doing anything other than what they are used to doing.
And of course, this is only the start. Google's move will get other search engines to also focus more quickly on this area, and so more and more people will be exposed to more and more fresh, original content - which can only be a good thing.