I am using Adobe Reader X (v10.1.1), and have noticed that the user interface varies depending on whether Adobe Reader opens a file standalone or from within a web browser like IE.
I prefer the interface shown from within a web browser (like IE), because it includes the Search Binoculars icon on the left-side. These Search Binoculars are so much more user friendly than Adobe Reader's default search box.
So, as a tip, make the UI consistent, and display the Search Binoculars by default.
NB: I know there is also an Advanced Search tool (which is a very handy tool in itself), however my comments do not concern this tool at all.