Where iPhoto really shines is how these tools are presented to people who might not have that much experience with fixing photos. iPhoto for Mac has always made this easy, but iPhoto for iOS visually represents these tools in a way that even the most non-tech-savvy person could get it. This is an app I could hand my in-laws and they would be able to fix a photo.
Rotating a photo is represented by either rotating your hand on the screen or adjusting a dial that lets you rotate and crop at the same time. Color adjustment uses common names rather than technical terms to address what you're doing. For example, in nature photos, you're adjusting "greenery" and "skin tones," which are easy to grasp. The most advanced tools are represented in a spectrum of paint brushes and tools that let you visually understand what you're about to do to your photo.
The help menu is robust. For each tool selected, activating the help menu lets you know exactly what that tool does and how to use gestures to do it. While I am not a fan of Apple's Marker font, used in the help area, it gets the point across in simple terms.
From iPhoto, you can export to various locations, but the most attractive option is the ability to create journals with photos. This is where some of the old iWeb comes in as you manipulate photos and arrange them on the screen, adding dates, quotes and more. It's not that customizable -- I'd like to see Apple throw in extra fonts and the ability to fine-tune pages a bit more -- but it does a good job at getting a basic album of images on iCloud. Yes, journal pages can be uploaded straight to iCloud, and you can share them via links with family and friends like the Mobile Me galleries of old. It makes sense for Apple to fold this functionality into iPhoto rather than break it out into a separate app.
iPhoto is $4.99, and it's one of the very first apps that should be loaded on any iOS device. With Adobe Photoshop Touch more than twice the price and not as user-friendly (13 tutorials? Really?) this is perfect to have on any iOS device for tweaking photos. On the iPhone, I can see this giving popular apps such as Camera+ a run for their money. It requires upgrading your iOS device to iOS 5.1 before you can install.