I am a big Remember the Milk user, and up until last week, was using Todo to sync RTM with my iPhone. RTM has since come out with a native iPhone app, and it’s stunning (and much better than Todo, in my opinion). Here’s the thought that led the company to create such a great app:
Building an app that simply gave access to your RTM tasks online wasn’t enough (after all, the web-based iPhone version does that already) The app needed to give you the power of all of RTM’s functionality in your pocket (Smart Lists, tagging, search, etc), take advantage of the device’s features (like knowing your location), and of course the whole thing needed to work offline too (it’s no good carrying RTM around with you if you can’t manage your tasks as soon as you’re out of phone or Wi-Fi range!).
The key here is simple: iPhone users want real applications that harness the iPhone’s power and ease-of-use, not rinky-dink wannabe apps that just get things done.