I've enabled the new gradebook in an online summer class that is just ending. As is often the case in online courses, there are many, many assignments, which can make the gradebook unwieldy to navigate under the best of circumstances. I'm finding the ability to filter by assignment group to a really big help as I work through grading final assignments and wrapping up the semester!
However, the persistence of the views was initially a bit disconcerting. When returning to the filter of a particular assignment group, I expected the view to default to the left-most column. Instead, it returned to the last place I had been working. I can see how this persistence might be preferable within a specific session -- but I found unexpected to return to the last place I had worked in a previous session.
(If this were a large-enrollment course where I continued working on the same assignment across multiple sessions, I can see how it would be useful.)