I tried reading up on effects, but the manual is not very helpful with specifics.
The emboss effect sounded good on paper, but in practice it's not really usable for me.
1. it seems to affect the whole image, including transparency. This is obviously not what I want.
2. I was unable to get highlights and shadows without the entire sprite getting desaturated at the same time.
3. The range of the effect is very limited. If the first two points were not a show stopper already it would only be suitable for very hard and thin appearances
I'm quite disappointed in the effects I've tried so far (except the water shader), because they are all advertised along with the rest of the features, and for the most part they are the same old well established effects I've been using for 10 years plus in various Adobe products: (glow, emboss, blur etc).
I understand this is not a software for artists, but I'd rather have a few well implemented effects than a wide range of choices that will never give me what I need.
If I had to prioritize I would say that in most cases something like emboss is not really essential to change at runtime.
But Glow for example is one of the most widely used effects in the industry and the current implementation simply does not do the rest of this fine software any justice. Having a more powerful glow effect would allow for creating higher quality graphics.
The beauty of it is: the tween posibilities are all there already! :)
Here's an example of how I applied simple glow effects working on the browser game Farmerama, using Flash. If you skip to 8:20