One whole area of functionality that is largely unexploited by most GTD app developers is dealing with the often perceived problem of overwhelm - of “drowning” in seemingly endless lists, feeling anxious about not finding things or overlooking things etc.
Non-GTD apps do not have this exact problem, not the same flavor of it, anyway, because these apps (and methodologies) are based on stringing up all the actions on a timeline (scheduling), which gives the users an illusion of full control. It also provides for a colorful, graphical interface. But scheduling has many serious disadvantages, as we all know, and GTD is firmly against it (except for objective calendar actions such as appointments etc; and objective “impossible before” dates, called Ticklers). The end result is that GTD apps often leave us with long “impenetrable” lists of actions; important and unimportant, large and small, related and unrelated, which many users of GTD apps voice concerns over.
I think it is perfectly viable (and not necessarily difficult) to create a set of related functionalities that tackle this problem area. Some or all of these features have been mentioned in other threads:
a colored “review attention” (or “priority”) indicator can help us see those actions that need special consideration during the particular type of visit to a list that we are now doing, e.g. the weekly review, the morning scan, recurrent during-the-day task selection checks etc. http://forum.gtdnext.com/t/review-attention-or-priority
elimination filtering (NOT filtering) can help us create one single list of good choices (with no false positives; and nothing missing) and will also enable us to use more specific context tags without increasing the overall amount of tagging work. http://forum.gtdnext.com/t/filtering-hide-show-etc
grouping of lists (by context, project, priority etc) can eliminate the initial feeling of overwhelm and guide our eyes to what we need to see even without having to filter
color coding of particularly significant contexts etc can further help guide our eyes regardless of what grouping/sorting we have in place at the moment.
a “since date” (historic start date) can help us use dates objectively and thereby reduce the counterproductive urge to schedule tasks to “arbitrary” dates in the future (that make no sense to us when we get there).
The combination of these little tools should not be underestimated. For example, Since dates would work perfectly in combination with “review attention” above (if during a review we discover that a dangerously long period of time has elapsed we can simply increase the review attention level). And color coding are a natural complement to grouping/sorting and to attention - combined, they can give us the essentials in a glance. And effective tagging and filtering would seem to be absolutely key to the whole GTD concept of selecting tasks on the go rather than scheduling them - amazing that developers have not exploited this, and no wonder at all then that so many users have concluded from these primitive apps that they have no use for contexts.
For any app it is essential to be strong in some area where other apps are not strong. Overwhelm is a general problem, especially in GTD and GTD apps. All apps are very weak and unimaginative there. GTDNext would have the ability to be the first one out to offer a reasonably comprehensive set of simple-to-use features that really help tackle this problem. And I am sure there is room for many new creative ideas that could further boost GTDNext’s position in this area. (And this would go well with the other potentially strong area of functionality with hierarchies and sequential control as a means to have overview of what is on our plate overall and how it relates to each other).