The Sort Orders are very limited IMHO if we can't drag-and-drop in that view. One important example is that I use nested subtasks a lot and then I carefully order those in the right task view with drag-and-drop.
One of the things that attracted me to Wrike was the ability to view a nested task in thread view. However in the right-panel this is not so and, as with other task management apps, all you can do is click on a subtask to then open it and view in turn its subtasks. That is a great way to lose track of the pipeline/order of your main task.
On the other hand in the left list you can see the entire task expanded with each level open displaying its subtasks. This is rendered somewhat useless however by the fact that this thread view can only be ordered by Date (useless in this case), Title (worse) or Priority (which has exactly three options).
To actually make UserOrder i.e. Drag and Drop useful is to
a) Allow this in list view and/or
b) Allow a Sort Order to be UserOrder
I find this to be a super critical requirement. It even applies to tasks w/o subtasks. Say I have a list of tasks I want a coder to do in particular order and want to save a Widget for that. If I make the List View filter by CoderName and TodaysDate and save that Widget he can then view that list each day. However if I can in the list view he is going to view then drag-and-drop and say Sort by UserOrder I think have usable daily task list that are prioritized beyond the basic and largely (to me) useless Low/Medium/High Priority