I've never had much luck with these. My dogs and cats usually find a way to circumvent the system.

Pros: Durable and easy to clean

Cons: my pets are too smart for auto feeders

they should be bigger, as they are so useful.

Pros: nice colors

Cons: is small

Not that feeding the cats dry food is very difficult, but the LeBistro Food Dispenser makes it even easier!! I have two cats and I only fill my Dispenser once a week. The food does seem to stay fresh, because even my finicky eater hasn't turned up her nose at the food -- or reduced her food intake. Plus the Dispenser stays really clean. I've had it for about three months, and I haven't needed to clean it yet (and I like things clean).
With so much time between filling the Dispenser, one time I did forget to check and fill it before it emptied completely. But the cats woke me early the next morning to let me know. It hasn't happened again.
Plus, I don't trip over the food dish accidentally any more, sending the food flying all over the kitchen floor. The LeBistro Food Dispenser is stable and large enough to let you remember it's there.
I admit, I got my LeBistro as a gift and I didn't think it was necessary, but I really like it now!

Pros: Only need to feed once or twice a week

Cons: Might forget to check food level with a week between feedings

This is just one of the feeders we have at the shelter. They are good to have for over night. The cats sometimes will tip them over. But, for the most part they are still up right by morning.

Pros: easy to fill , easy to clean

Cons: none

These food and water dispensers are great for daily use, or for use when pet owners are travelling for a few days at a time. Just fill them up and they are good for several days to a week. The only problem I had was that my cat liked to drop food into the water dish, which, if not removed in a timely manner, would become soggy and float to the top of the jug, making it necessary to pull it apart, clean, and refill it almost daily. Not a problem if you are able to keep the food and water separate from each other, but we live in a small home where this is not possible. I beleive newer designs MAY have addressed this problem.

-- additional:

[updated on 2008-02-12 20:00:13]:
Sorry, I don't know why it says rated 1 out of 5 on my review. It should say 4. It would not allow me to edit it.

Pros: Don't have to worry about running out of food or water

Cons: Food dropped in the water dish floats to the top of the jug