When I read this article a week ago or so I wasen't so excited from the improved search interface - Until I gave it a try.
Please note: in order to upgrade you will need to expire the cache of all the repositories - the improved search is a result of new lucene indexes included with 1.7.x version.
Nexus Open Source 1.6.0 released, April 19th to be accurate, no breaking news, its just out there and with many bug fixes ..., See official release notes @: