In fact, you would be surprised at the many simularities in what needs to be done to take care of saltwater aquariums relative to freshwater aquariums. The main reason that saltwater aquariums are generally considered to be for experienced aquarists is their cost. Not only are saltwater filtration systems more expensive than freshwater ones, but the cost difference between fresh and saltwater fish is huge. The bottom line is that saltwater aquariums are for anyone, aquarium veteran or not. However, you must be serious and commited to the aquarium.
Freshwater aquariums are also a little more tolerant to lack of cleaning.
I know of people who change their water once a year in a freshwater aquarium. Do this with a saltwater setup, and you will be lucky to have fish in two months. What I have learned is that most people find water changes annoying. While water can easily be added to a freshwater aquairum, saltwater aquariums require you to mix the water with salt first. Amazingly, this small difference is all that it takes to make people get too lazy to do regular water changes for their saltwater aquairum.