I have worn varifocals for years and love them. It just like your eyes would see naturally at any distance. There is no line.
Two things though. First it can take two or three weeks to get used to them. It's your brain that has to get used to the lens, not you.
Second, go for the best quality lens if your optician offers you a choice. You have a far better chance of getting on with them if you do this as. There is greater variation in near, middle and distance vision, with the better quality ones, so they are more affective and easier to get used too.
I really don't know I am wearing mine, unless the lenses are dirty.