eBay appears to be attempting to replace some of the old categories with item-specifics and filters, so that it will (potentially) be easier for users to find items in the future. Previously, if a seller listed an item in the "wrong" category, that made it very difficult for users to find the item. Categories are being simplified somewhat to make it harder to list an item in the "wrong" category. Users that have grown accustomed to the old system may have to change the way they are used to browsing or searching a bit, but the old searches should still be able to be done one way or the other.
If you are looking for particular items and having trouble searching, if you provide a general description of what you are searching for, someone may be able to suggest a link as a starting point for your search.
The search technique that seems to work best for me is to start with a search using some keywords, general or specific. If you are trying to search a particular category, try using keywords from the category name.
From the search results, change the category if necessary using the links on the left side of the page -- the keywords and category help to determine what filters are available. Finally, choose some relevant filter options to narrow down your search if you are still seeing results that do not interest you.
