I've been interested recently in the apps available for iOS that push the very edges of what we thought was possible on a mobile device. Informed by my recent experience of spending a week on iOS alone, I decided to try and express what I mean by "ambitious" and to collect some examples of those kind of apps.
When iOS first appeared, it was a smartphone OS. Today, with the iPad, it's much more than that. To be an "ambitious" iOS app, I think you need to be doing one or more of the following things:
You push the performance boundaries of the platform.
Some great examples include Real Racing 2 HD, ArtRage and Collabracam. These are the applications that we all once thought required far more power than you would ever see in a "mobile" device. Sure, they're riding the crest of Moore's Law pretty hard.
You attempt something on a scale that's amazing for a mobile device.
The canonical example is GarageBand: an 8-track recording system and playable virtual instruments, all on an iPad, for £2.99? Unbelievable. Similarly, the feature-completeness of Keynote for iOS is something that's constantly inspirational to me - down to things like supporting Magic Move and control via the Keynote Remote app.
You enable an entire task or workflow to be done on iOS alone.
A recent example I came across is Book Creator which lets you create fixed-position eBooks on your iPad, then send them to iBooks right on the device to test them. Build an ePub right on your iPad. Other examples include many of the Omni apps, which are approaching the power and scope of their desktop counterparts and, in the case of OmniFocus, probably exceeds the desktop version.
You make something possible that was never easily done on a Mac.
These kind of apps are taking the touch-screen and radically redesigning the task to take advantage of that screen. A first simple example is the Maps application - how clunky Google Maps feels in the browser after you've used it with fluid pinch-to-zoom on an iPad.
Other great examples include djay, which turns your iPad into a pair of mixing decks. The various Toca Boca apps are also fantastically engaging for children in a way that you don't imagine they would be when used through a keyboard and trackpad.
So those are my (rough) criteria for being an "ambitious" iOS app. It's important to note that merely being a well-executed (or the best-executed) example of the type doesn't feel like quite enough. For example, the loveliest book app in the world doesn't really cut it for me. That's not to say those apps aren't carefully and wonderfully designed, or that they're not technically challenging to execute well. It's just that I'm looking for those apps that re-shape the way people perceive the power and strength of iOS.
Anyway, to capture these, I set up a free-to-edit Google Spreadsheet. Feel free to add apps you think should qualify. Please don't just add your favourite app - do explain why you think the app qualifies as "ambitious". I reserve the right to prune the list as I see fit. Note, too, that I'm not just asking about "education" apps - I'm looking across the entire platform.