iPhoto is Apple's flagship application for managing and viewing photos on your Mac.
The interface is very slick and iPhoto features tons of tools to help you manage your library. In fact, the real strength of the program resides in the organizing options such as organizing by events, create a gallery, print out calendars and books etc. In particular, the unified search function allows you to quickly find any photo based on all sorts of criteria like date, name or keywords and now, even faces.
One of my favorite features of iPhoto are the photo montages which allow you to select a style of presentation with accompanying music. These look great and are a nice way to view your photos and reminisce on the past. However, I dislike the way iPhoto has to build a library file of your photos. If you've already got several GB of photos on your system, you don't want another huge iPhoto file taking up space on your hard drive.
Of course, iPhoto is also very well integrated into other Apple apps such as iDVD so your iPhoto images can easily be used in videos that you're editing. Displaying photos in full screen mode isn't as simple as it should be however - it involved way too many clicks and its hard to get rid of the toolbar.
Overall, iPhoto is an extremely elegant photo application which makes viewing photos a pleasure.
