Zoner Photo Studio Free is a simple image editor and manager. If you're looking for a quick way to change contrast, remove red eye etc, this is a neat solution.
There are three main elements to Zoner Photo Studio, the Manager and the Editor. The Manager lets you find and organize the images on your PC, the Viewer lets you view them, while the editor allows you to make simple changes to your photos.
The viewer is attractive, but nothing special, but the manager is good. The interface is simple enough, with a folder tree, browser and information panel. You can email images from Zoner Photo Studio, and apply filters to make finding them easier. There isn't anything revolutionary about the Manager, but it does its job.
The Editor is better, offering a range of useful tools that will allow you to improve or alter photos you've taken. It's not as powerful as Photoshop, but it's much easier to use, and has the tools that most amateur or casual photographers will need. Zoner Photo Studio has a 'quick fix', which basically makes the image a bit stronger, and you can also play around with the color, levels and resize as well. There's a red eye removing tool that works well, as well as more subtle things like a clone stamp tool. In this free version, it's really only the lack of proper layer tools that are missing.
Zoner Photo Studio is a good option for basic photo retouching and editing, and has enough tools for most users.