When using the navigation buttons, prior searches are no longer remembered. So if I did several searches in a row, I end up navigating back through several pages of the same (most recent) search results. My preference is for the previous searches to be retained, but if that's not possible then the search results pages should probably be treated as one "back" entry rather than multiple.
Edit: just to clarify, it can distinguish between middle click/context menu searches (ie "artist is Fleetwood Mac" in the tab) and search box searches ("search results" in the tab). It's mainly multiple search box searches that seem to be a problem.