The new User Story Map functionality is really good and we've started using it for some cases. What would be really useful is to be able to configure the cards in the say way we can on the feature boards. This would allow a user to select the different fields which are visible from the data model (for example integration ID, assigned user) so once you'd created the map you could then track the status as you would from the features board.
Also would be nice to be able to switch between a small and expanded view as you can on the features setup. For items with large numbers of items then being able to reduce the un-used space and see more items would be helpful