The editing features in this app are more or less the same as others. What makes Darkroom stand out from the others though is:
- an excellent UI
- powerful curves edits
- unlimited history
- the manner in which it utilizes my photos library
- speed/responsiveness
Bottom line: if Im not editing photos in Lightroom or Photoshop on my desktop, Im editing photos in Darkroom on my iPhone.
R0bw about Darkroom: Photo & Video Editor, v1.1