We used to leave our cat at home for a week at a time when we went on vacation. We would have a neighbor come in once midway through the week and check on him, change water, add food, etc. He was always fine- he was a grazer, and had food out 24/7, so it wasn't new for him to have food out all the time. He was a real "Velcro kitty" when we came home, but was fine while we were gone.
Since he passed away, we got 3 new kitties. They are meal fed (weight issues). Since they are used to having food put out 3 times a day, and no food out for "grazing" all day, I feel like we need to keep them on at least somewhat of a routine. We do have dry food in digital-timer controlled feeders, but I also have a good friend and neighbor come in once a day to feed them their normal canned food.
I guess I am saying it depends on how you feed the cat, the age and general health situation of the cat, and how comfortable you are with leaving them. If it would ruin your time away, worrying the whole time about your cat, go ahead and find someone to check in on it. I'm sure kitty will be all right, but for your peace of mind, if you need to get someone, do so.