The best change is that they have drastically sped up the site. I dunno did they add more servers or simply optimise their queries (I suspect the latter) but the site and particularly searches are now running a whole lot faster.
The next great change is that they have moved the blog searches to a page of its own. You can now find blog searches at s.technorati.com. The searches return relevant results and make subscribing to searches a whole lot easier than heretofore.
Overall, the new design seems to be getting the thumbs up from most reviewers. This can only be good as with the rollout of Google’s excellent Blogsearch tool, reasons for using Technorati were becoming fewer and fewer.