It appears to me that this is a uni-directional method, i.e., there is no history available if you need to save and restart. If you've not kept an un-modified layer to restart from, all you've got to work with is your partially modified image. There is no way to back out the sharpening, but you can add blur. There is no way to back out lightening or darkening other than to darken or lighten the current image.
It's not clear that this is a problem, but it is a concern.
Alan