Despite a kind of a whacked out difficulty curve, this is a lot of fun.
The graphics are definitely a bit different than the original Super Mario Land. The original had graphics a little better than the original Super Mario Brothers on NES and this is more on par w/ Super Mario Brothers 3.The most major difference the Mario sprite is much bigger and better detailed. Consequently, you can jump very high, almost to the top of of the screen, and the game feels a bit small comparatively. There are definitely sections here and there where you really wish you could see less details of Mario and more things going on in the level. The music is good too. It avoids rehashing classics and is an all new sound track as far as I can tell. All and all, the presentation works pretty well.
The plot here has something to do with Wario stealing Mario's house and making him find the titular six golden coins before he can re-enter his own house, which is for some reason booby-trapped and very highly anti-Mario. Go figure. Of course, to get these six golden coins, you have to go through six levels each made up of about four stages. There level design is quite varied with the normal smattering of land and water levels plus a space level w/ some very different controls. You can attack the levels in any order you chose and they are all at approximately the same difficulty level, which is rather easy. Even the bosses don't add much of a challenge. It's rather forgiving too. If you lose all your lives, you simply have to re-beat the bosses, which is more of a pain than a challenge. Of course, in 8-bit land, nothing can be too easy and so the final level, Mario's inexplicably Mario-adverse castle, is unreasonably tough in comparison. There is some serious platforming here and no save points whatever. Wario himself is pretty simple in comparison but getting to him is a heck of a trip. This is not Lost Levels-level toughness but it is as hard as any point in pretty much any other Mario game and you're just not really expecting it. In the end though, a few hours practice will get you through and it's quite satisfying though I'd imagine most people will spend about equal amounts of time beating the rest of the game as they do finishing the one last level. That to me is not quite right but it does not ruin the game by any means. By the time you've gotten to the last level, you've invested enough time to make beating it worth it.
In addition to the main game, there are also a few bonus levels that you can get to by finding alternate exits to some of the main levels. These are all just more of the same but finding--which can be tricky if you can't keep yourself from peaking at a strategy guide--adds a lot to re-playability.
The simple fun of Mario cannot be denied and, as long as they keep the simple, intuitive gameplay and fun level design, Nintendo could keep making Mario games forever and people would buy them. This does all of that and adds some unique elements as well. It is definitely worth the half-dozen or so hours of gameplay it takes to beat and more time beyond that.