Even as an alpha image editor, I think it's safe to dub ChocoFlop a true "poor man's Photoshop." It offers layers, real-time preview of filters and effects (of which there are many), a slew of selection tools, blending modes, masks, color adjusting and a whole bunch of file formats it can save to and even more it can read from - including many versions of RAW. For the full details, check out the longest image editor feature list I've seen in a long time.
As an alpha it's free, and the author has stated on his blog that, once it goes official and commercial, ChocoFlop won't cost more than $50 USD. I haven't cracked this open yet myself, but if you've been looking for a powerful image editor that offers quite a bit more than the standard CoreImage-based options out there, ChocoFlop should be right up your alley.