Midnight Beep (http://www.midnightbeep.com) recently put a lot of effort into their GTD-app Inbox. There is an iPad version called Inbox touch that seems quite well made. As the former posts seem to refer to the classic version (that was actually quite quirky...), no one seems to use the new, much more sophisticated version. I'd be interested in why that is and - if I am wrong - in the experiences people had so far?
All the best from Berlin