True timeless masterpiece.
I've played it for the first time just now. And luckily did it on original hardware.
The game is super enjoyable and fun. It gives you optimal level of challenge. It's not super easy but not too annoying with hard levels. Just several bonus levels made me try them for dozens of times.
Secret exits gives the game second breath after main storyline is completed. It was really interesting to find them all. 5 times I had to find help online - exits were hidden too strongly. And probably that's the only negative feeling about the game.
Animation and sound are great. I didn't get tired listening to music themes again and again.
That's nice to see how such ancient versions of Mario games already had some key mechanics of the series which we know today. That's a true delight for me. Even can't imagine how inventive all these things seemed to be back then.
So totally recommend for everyone who somehow missed this gem.