uPhoto Quick Viewer is an application that lets you import your pictures, view and edit them and create slideshows with them.
As an image viewer, this tool leaves a bit to be desired, especially because it doesn't feel like a viewer at all. After you have imported a folder or a group of images, they will be displayed in thumbnails within the application. When you double-click an image to view it, Apple's Preview app is launched. So, this viewer doesn't really let you view your images, it just opens a separate application to do that. I can do the same from Finder. I tried pressing the spacebar with an image selected to see if Quick Look was available, but nothing happened. Basically, a few seconds after launching this app, I was able to discard it as a series photo viewer. I still proceeded to check the other features available. The slideshow is the one feature that I like about the app. It displays your images in full screen. They are switched automatically and you can even add photos to iPhoto from here.
In short, uPhoto Quick Viewer isn't really a quick photo viewer. Finder, Mac's file browser, is a better viewer than this application.