An excellent question.
1.
Two category filtering for device to desktop syncing. I've been lamenting this ever since Intellisync announced an end of life. I use this feature to keep my personal items out of my work calendar, tasks, and contacts.
2.
The ability to categorize and filter my email. This is a feature that came up lately. Mostly I think out of Gmail envy.
3. Other usual suspects mentioned a million times before:
- Easier OS updates
- Better Memory management
- Better multimedia experience
- etc...