Kayaks are narrower and can get into places you would have difficulty going in a flat bottom boat. Thay are also much faster (unless of course you have a motor) than a flat bottom aluminum. They are also lighter and much easier transported. A kayak can go all day in 6" of water. Can also slide it over logs and stuff in a creek. No question about a flat bottom boat being more stable and comfortable though. Sort of like comparing a motorcycle to a pick up truck. I've rolled mine several times and and except for the one instance I was sliding over a beaver dam it was when I was getting in or out.