The upshot of the latest app store search update appears to be it searches the title or the keywords, but not both at the same time. Take my app Onsite Time Tracker as an example.
A search on the title "Onsite" the results are the same (position 3).
A search on some of my keywords (location timesheet) the app has gone up from (6 to 2).
A search on a mix of title and keywords (onsite location tracker) the app has gone down (from 1 to not listed).
These results came from appcod.es
Edit: On June 29th, this issue was resolved by Apple.