At the moment, I'm using it as an outlining tool for a programming book I want to write.
I find TreeSheets unique and brilliantly designed. I do not like either sticks in my wheels or wheels in the mud. I find it fits my needs for light and agile.
My preferred tools over all others: TiddlyWiki (for dealing with complex intertingularities, so that they submit to my will), FeatherWiki for very simple things, and TreeSheets for complex information that is hierarchical in nature.
It is really worth going through the tutorial, and then trying it out to organise some complex information.