Hardest Mario game

This is by far the most difficult Mario game I have actually beaten. It took me months. If it were not for the save option Super Mario All Stars gave us, I never would have beaten it. Has anyone else played it all the way through?

I never beat the original three American Mario Bros. games for NES because I was so young, and I was a horrible video game player. By the time my skills developed the NES era was long gone.