Ultravisual (free) joins a large collection of photo-sharing apps for iOS, but it has some unique features wrapped in an attractive, but at times frustrating, GUI.
The app lets you load photos from your camera roll, and arrange and label them into an attractive presentation. You can also collaborate with others, and you can include videos in your collections. Getting the images in any order is easy with a drag-and-drop interface. You can take photos from within the app, and there are filters that work in real time for things like warming up the color balance, but oddly, those filters don't work after a photo is taken.
Labeling of photos uses very attractive text, and the finished presentation looks very nice. Videos can be edited in-app, and strung together. These are nice capabilities in a free app.