My simple test with it was:
* make folder to stick sprites in
* draw 6 simple sprites (and I do mean simple)
* set where I wanted them to be
And bam, there they were, all ready to be used in my project. There were a few things to tweak here and there, but those are mostly extras, and not necessary to (how do you want to sort it onto the sprite, how can Texture Packer adjust it to fit etc).
I'll likely be converting my RPG's Battle Engine Animation System (RPGBEAS?) to it. What I had currently was SOOOOOOOOO clunky and inflexible (if I wanted 1 animation to have 30 frames, while most had 2 frames, then I had to extend the entire texture so everything supported 30 frames. What a waste of space!)
This should also allow me to go balls crazy on special attacks (Knights of the Round from FF7 anybody?)