I really like this app. Easily to use. Easy to create my own watermark and put it where I want and the feature to put it on all images at once instead of individually is nice. However, this feature is not useful if your images are slightly different sizes or vertical vs. horizontal or if the focus of the images is in different spots.
Super happy with my purchase though. As I will use this for all my work since I do editing on the go with my iPad.
mriva about iWatermark - Watermark Photos, v6.4