The Keyword Tag filtering should still work as previously. It should still be showing AND, only showing those files that have "Tag 1" AND "Tag 2", those that only have "Tag 1" OR "Tag 2" will not be displayed.
Are you seeing that all images that have either "Tag 1" and/or "Tag 2" displayed? Could you post a screen shot of this happening? (Simply hover your mouse cursor over the tag icon in the lower right of an image to get a Tool Tip of the Keyword Tags applied to that image)