This is definitely the only reason I still play my NES.
I pop it in once in a while (and hit the ancient system a few times to get it working), and I venture back in the good old days before XBox and Gamecube.
All I can say is...wow! This game is the best Mario game I have ever played! The controls are easy, the fun level is off the charts, and the difficulty is moderate. It has 8 worlds: Grass, Sand, Water, Giant, Sky, Ice, Pipe, and Dark. It would have been cool if there was a Fire level, but what are ya going to do? Each world has between 6 and 10 levels, between 1 and 3 mini-dungeons, and a whole lot of other things, like Hammer-Bros. and Toad's Houses. There are only two problems with the game, which are actually good in perspective, The first is that there is no save feature. The second is that the whole game, without skipping levels or cheating, takes approximately 3 hours to beat, and since there's no save feature, this may be a problem. The way I see it, if this game had a save feature it wouldn't be have as good. It would be too easy. Also, see Replayability for my views on the time it takes to finish the game.
I love the music in this game. So much that I'll sometimes hum some of the tunes from the game even if I hadn't played it in a couple months. Even though it's a little bit repetitive, it isn't annoying. Also, some music from the original Mario game has been recycled and improved in this version. My personal favourite is the Sand World music. The sound is also recycled from the old Mario, and, yes it has been improved. No two sounds are alike, whether you're kicking a Koopa shell or going down a pipe.
The graphics are great in this game. The best in a NES game I have ever seen. All the colors are crisp and clear. Mario looks 300% better, and he actually has an outline now! Goombas don't look like they're wearing glasses anymore! The only annoying problem I find (and it's only in rare cases, at least for some people), is that if you find yourself in a crammed position, preferably with a wall there, you'll most likely get stuck. This happens often for me, even when I try to avoid it. This glitch brings the graphics grade down, but hey, you don't have to restart the game. Just wait until time runs out for that level.
I'll give you 3 guesses on what the story is. Nope......Nope.....Yep, that's it! It's about Mario saving the Princess from Bowser...again. Yawn.
Without this, this game would be nothing. This would just be another one of those games where you struggle to beat it reluctantly, and when you do you throw it out the window. Not a chance. I don't know what it is, but I can't stop playing this game! Going back to Gameplay, where I mentioned the 3 hour game time it takes to beat. OK, if you're on World 6, and you have to go somewhere, you won't mind turning it off. You wouldn't care one bit that you would have to restart the whole game. Even if you beat the first World, you wouldn't mind at all if you had to restart. You just wouldn't care! You could restart level 1 10 times and you wouldn't get bored with it. As I said before, I don't know what it is, but it rocks! EVERY GAME SHOULD BE LIKE THIS!!
Seriously, if you have never played this game you should seriously make the effort. Buy it for two bucks, or even buy an NES for 15 bucks! It's worth every penny. Now if only the other Mario games were this good...