Looking at this legendary game decades away is somewhat of a futile exercise, as everything good and bad about it has already been penned by anyone from respected critics, to dummies with only a passing knowledge of the game that arguably made Nintendo what it is today... of course, since I have nothing better to do, why shouldn't I indulge in adding my two cents to the fray?
Don't worry, I promise I'll be brief :)
With it's blend of trippy, fantasy levels, cutesy enemies, smooth scrolling and perfectly refined game mechanics (that remain the template for the genre to this day), Super Mario Bros. managed to bring a level of arcade gaming perfection previously unheard of in home-based videogame systems, and provided an original experience unrivaled anywhere. The story has been chronicled everywhere so there's no point in reiterating it, but the results are baffling: with a simple design evolved from the basic run'n jump games that preceeded it, the designers managed to hit that nail of game design that such games as Tetris or even Doom also got: simple, but detailed game mechanics, challenging arcade gameplay supported by a perfect control scheme, smooth graphics and sounds to complement the gameplay, and lots of imagination poured into unique creatures and levels, devious jumping puzzles, etc.
Interesting to note that a storyline is never a big consideration in any case, uh? I'll leave that for someone else to discuss. In any rate SMB manages to be one of the holy classics of gaming due to the sheer FUN it is to play, an enjoyable ride from start to finish as you embark on the rather silly but engaging quest to save the sterotypical maiden in distress as an excuse to sort out the many challenges laid for you on each level and longing for the challenges that awaited you on the next carefully designed level (not a trivial matter, as any game of that era can prove, when advancing levels the games merely recycled what had been done before, adjusting the difficulty or simply speeding up gameplay (see: PAC-MAN) Mario on the other hand offered unique challenges in different settings and with different moods (thanks to the excellent graphics and sounds of it's day, which allowed a full soundtrack whose main theme is nothing short of an anthem for a generation of gamers [myself included in a somewhat uncanny and frightening way, as I'm able to almost mystically recall the tune years away as if it were some type of racial memory!]).
All that plus a lot of strange underlying themes that have always to it's charm when viewed from the warped eyes of an adult mind (Eating a mushroom makes you "higher"? Yeah, like Peyote right? A "flower" that makes you shoot fireballs? Mushroom-People turned into blocks? (which you get to break!) Jumping plumbers?? To this day I wonder just what kind of fumes the developers of these types of games inhaled, either that or the designers where trying to tell us something all along... probably a pro-drugs message of some sort.
Probably the only problem with Mario is that as the Mega-blockbuster title of it's day, it was copied and cloned to death, making it so that pretty much every console to this day has to have a cutesy mascot platformer with trippy locales and gameplay based on the same grounds as Mario's (run'n jump through many levels, facing a boss near the end, doing whatever makes him angry three times, and then repeating until you get to the princess or whatever it is you need to find).
The 2P mode was pretty crappy the way I see it, and I also disliked the fact that you had to beat the game in one sitting (reason numero uno for me to hate early console-based platformers) which coupled with the large number of levels made it more of a challenge than I was willing to handle at the time (I mean, C'mon!! You keep rescuing the princess and it's just a stupid retainer over and over again!! What the fuck?? Am I not good enough for her???).
...Oh yeah! And the movie!! BWAHAHAHAH!!!!!!!!!
The Bottom Line
Just a little game that spawned an entire genre, cemented the most well-known videogame mascot ever, and sold billions of copies worldwide. A pretty good achievement for a company that used to make cards and a game based on the acid trips of a couple of plumbers stoned out of their minds.