If you have 10.4 you already have most of the functionality of this program:
* Automator.app - you can easily make workflows to batch resize/rename/convert images
* Preview.app - has sharpen, brightness, sepia , etc, via the Image Correction palette though no batch processing of these effects that I know of
That being said, the programs features are reliable. The presets feature is a good idea.
Unfortunately, the interface is a bit clumsy. Hopefully within a few revisions it will be cleaned up. The interface makes it hard to fully utilize the great features they have implemented.