I’d be afraid I might scratch it. Scratching your new canoe or kayak is a forgone conclusion. They are meant to be paddled and a fresh coat of varnish every second or third year (depending on use) will see those scratches disappear.
One learns to be a better paddler: not dragging your canoe or kayak up on rocks or tossing it into the back of a truck. I always bring my canoe up onto a shoreline by putting it down on my life jacket – quick, easy and safe.
Are they easy to repair? For the most part, yes. Even punctures are quite reparable by a competent builder. Rot can be a problem if stored in the open. No watercraft, either wood or otherwise likes to be out in steady wet or sun.
How long does it take to build one? I build three canoes a year. More than that and it becomes manufacturing and I don’t want to do that. This leaves me time to do other woodworking projects and to enjoy the watercraft I make!