Nice clean look, but could be hard for those who don't use search
The search needs to be very good since this site communicates so much information on a regular basis. I like it, but i know from usability tests that if your demographics are mostly people over 50, you'll need to make the search field very large and prominent or they wont use it.
Also, I've never used a search box. I'm used to seeing what I want, or links to what I want. Your search-dependent site model is confusing.