Several years ago, Kodak introduced a new film format called the Advanced Photo System (APS). Many camera manufacturers have since adopted APS and now make both APS and 35mm point-and-shoot and SLR models.
APS film is smaller than 35mm film--it requires a mere 56 percent of the area that a 35mm negative uses. The smaller negative allows for a smaller film canister, making APS cameras the smallest and lightest cameras on the market. Another plus for APS is that loading film is absolutely foolproof. The self-contained APS film canister makes it almost impossible to improperly load or accidentally expose your film--you simply drop in the canister to begin shooting and then remove the canister when the roll is done. The canister also has handy indicators that let you know if your film is unexposed, partially exposed, completely exposed, or developed.
The APS format makes it easier to get reprints as well. When you get your film back from the processing lab, you receive an index print with thumbnails of your photos. You also get your negatives back inside the film canister, making it harder to lose or damage them.
APS cameras allow you to choose among three picture formats for each shot: classic (6 by 4 inches), wide-angle (7 by 4 inches), or panoramic view. When you order reprints, you can request a different format for the reprint than what you originally used for the photo--for example, if you took a classic photo, you can later reprint it as a panoramic. APS film also uses a magnetic storage system, which allows images to carry "cheat" messages for the film developer; for example, if you shot a picture in poor light, the cheat message tells your developer and he or she can try to compensate during the printing process.
The greatest downside to APS cameras is that the reduced negative size results in inferior picture quality. While the effects on standard-size prints are negligible, if you enlarge APS photos beyond 5 by 7 inches, the image becomes less sharp and more grainy.Another disadvantage is that some photo labs are not equipped to develop APS film. As many 35mm cameras offer comparable features, such as date imprinting and panoramic mode, and tend to offer a wider array of artistic options, 35mm cameras are still the favorite pick of most seasoned snapshooters. Finding 35mm film is also often much easier to find than APS film, particularly if you are traveling.
Source: Amazon.com Camera Buying Guide By Cintra Pollack and Walt Opie