Well, simply put there are two reasons:
- lack of Android support (I think ignoring the largest smartphone platform is just fanboi silliness)
- quirky sync whereby I need to have devices on the same netwrok, fire up Things on both, then hit “sync” – may have been hip in the 80′s, but now I want seamless cloud sync
What have I replaced with?
But the very nice (and free) Springpad of course, which comes in iOS, Android and web flavors.

Welcome to the herd.
Or rather springpad! :P I hope you’ll learn to love it as much as I have!