I feel that ppl over exaggerate a lot of things, but they ain't lying about salt water. It's not necessarily hard, but there's a lot of science involved and you gotta be willing to learn. Once you get your salinity right and have enough live rock to convert your nitrites to nitrates you're good. Frequent water changes is a must and you absolutely need proper lighting if you want more than just fish (inverts, coral, etc.). There's a significant difference in the price of maintaining salt water compared to fresh water, though.