So basically, you start it up, and on the left, you have the folder structure and the path is on top. Then, to the right, you have the list of all the images in the directory, and if you click one, it will preview it. Then when you open it, it opens either fullscreen, or in a regular window, at the image's full size. It's kinda nice that you can view pics full screen and then have a slideshow, but then Windows Picture and Fax Viewer already does that....so....*shrugs* You can also delete, move, or copy images in the program.
That's about it for viewing. But there's something else that really surprised me, and that's that this little program has a fairly nice image editor.It has flip vertical/horizontal, resize, sharpen, convolve, and then some artistic, blurs, and ripple effects. Plus it has color effects like contrast, lightness/darkness, and saturation. Not bad, not bad, at least for image editting on the fly. One problem though.....No undo. So if you make a mistake, you're not screwed (since it doesn't autosave the image) you just have to start over.
The only other thing that I've have to say is that you can't set it as the default program for images, or open images with it. By that, I mean you can't create a context that says "Open with Pic Viewer" or you couldn't drag a JPG onto the Viewer.exe to open it. In other words, you can only view and edit an image by launching the program and then navigating to that folder, which is really annoying. But I mean, it's still a good program, that would just be a nice feature. I would use it instead of Window's default if it did.