It's one of my favorite famicom games.
Also it brings memories as it was my first unrestricted NES experience and the game I had spent a day and night with when I first time borrowed the console from a friend in my childhood.
It's a really awesome platformer with nice visuals, most beautiful soundtrack and a great gameplay. It's not hardcore to the end like some Japanese titles of the era could get, but it requires some skill.
I've played the game through multiple times on different emulators. Actually I use this title to test anything that can play NES games, because I just love playing "Mitsume ga Tooru" again and again.
Finally I've bought the game for myself, I just ought to.
It's definitely a classic everyone has to experience.