Some of us work in contexts where we have to open some tools and wrap our minds around what we're doing in each context before working on a task or group of tasks. So, being able to see tasks organized by context would be important. Similarly, seeing sub-tasks organized into a project would keep a group of tasks in their context. Only after that would linking to a third-party calendar make life easier. A lot of non-iOS people use Google calendar, so a link to that should be a priority. If EN can't get an API set up, then please show us a workaround like the tiny URL idea mentioned above.
Please also let us see all tasks organized by projects and contexts or by day/week/month in a single window with a few columns so we're not getting lost in a long single column. Let users be able to decide how the columns are organized - by context, by date, by project, by context & project, etc. - and allow a column with a short group of tasks to start a second group after an inch of blank space so the value of columns isn't harmed by some having much less content.
Notice that some people posting above are more calendar-focused. Sub-tasks would need to have their own date & reminder capability that users could by default link to the whole project/group of tasks and decide which to give separate due dates and reminders. Users would benefit by being able to see tasks by date-view and then by project-view.
All of the good ideas mentioned in people's posts in this discussion work within a system. Are there simple tutorials showing how to use EN tasks within a modified GTD system (where tasks have contexts) connected to a Google Calendar on Android and Windows? And similar tutorials for iOS users?
P.S. Thanks to all the contributors making this a constructive discussion.