what I particularly like is the ability to 'paint-in' fills - especially where the line art is [intentionally] 'wobbly' and there are [again intentional] gaps - I find it much more natural [and quicker] to 'paint-in' behind, and erase the odd overshoot, than to [IMO laboriously] hand trace and then shift the nodes around to make it fit - I guess it depends on whether you are a freehand artist or at least prepared to go that way