I'd say there's one primary "potential to improve" - a mobile app. The situation is better than it used to be, but frankly still not good enough IMO. Otherwise, an org-mode + Dropbox combo works perfectly for me; every computer I own or work on has Emacs installed anyway.
And it's hard to note down so much content on mobile that you won't be able to retype it back on a proper computer under 5 minutes.
I've used org-mode for todo/gtd/planner for years before I had my first smartphone. Then I suddenly realized a user friendly mobile app is so much important. I started to add some of my todos to my phone's builtin reminder, and as you would expect, my todo system quickly fell apart. I'm using omnifocus now on both my laptop and phone, and I would pay more for an equally good interface on the mobile for org-mode.
I still use org-mode for writing everything else. Nothing competes with that.
I googled and couldn't immediately find a thing that eats notes from IMAP into org-mode. That could be pretty useful for capturing on the go, since e.g. iOS Notes does good IMAP sync.
And it's hard to note down so much content on mobile that you won't be able to retype it back on a proper computer under 5 minutes.