isometric tile handling for one, that'd make it extremely useful for game mockups and ISO visualization.
multiples of 45° or "iso" angle.
that's not the primary iso angle, neither dimetric or trimetric (2&3 pixel steps(and major forms of ISO)) are 45° only a select few games do 45° angles, and also GIMP for one does not have a snap for dimetric or trimetric angles, (but with a grid it's easy to do manually) so that alone would have a great advantage over alot of drawing tools
the feature that'll make this the most attractive would be multiple layer tiling support angle.[/quote]
that