1. Folders to sort games. Although this has become less important since the update that allows for alphabetical sorting.
2. Themes, because some customization is nice.
3. Virtual Console, because providing gamers with the choice between ownership and rentals is better than no choice.
4. XL Joy-Cons with bigger sticks, buttons and a d-pad.
Other things such as better battery life have been standard for revisions of portable Nintendo consoles, so it's redundant to mention them.