Great... but still over rated.
GAMEPLAY
Nintendo pulled off a simple concept, and turned it into a great game 2 decades ago, and that concept still works today, just as good if not better because of the technology. The movement is smooth, jumping feels good, powerups are good. Think Mario Brothers 3 without the raccoon, and with the Mega and Mini Mushrooms and Wallkicks and you get the gameplay in NSMB.
There are some kinks unfortunately. Boss battles are extremely repetitive, featuring the exact same mini boss (okay it changes once but whatever) and a boring final boss. They don't even change the way to get to the other worlds. Its the same way to get to both of the extra worlds. The game is not difficult until the last few levels, but before then I only died a few times because I was careless. Its very easy to go through worlds 1 - 7 without dying more than once or twice. The game is never overly challenging even at the end though, so it never gets harder than relatively easy.
If you want to go for extras, there are coins in every level to collect, and you can purchase stuff like extra paths with them. None are too difficult to find, so it doesn't add too much time onto the game, and doesn't add too much difficulty
Mini games have mostly been seen in Mario 64 DS, but now with multiplayer!!!. I did have some fun with this, though many are too simplistic for more than a day or play.
GRAPHICS
Graphics are top notch. High polygon models, colorful backgrounds, good effects. Everything you'd expect from a first party Nintendo game. Just don't expect anything out of a 2D plane though.
SOUND
The game suffers there. Mario's voice is back, for better or for worse. It never really bothered me, and seemed to add something to the game than if I muted the volume altogether. I'm not sure if its just me, but I disliked most of the music in this game. It wasn't up to snuff with classics such as Mario World. Some I turn the volume down because I heard them way too many times. The castle tune is catchy unlike the rest though, and I did enjoy it. Unfortunately, the first levels song is the song used in most levels, and its the one that got on my nerve. After hearing the great music in other Nintendo series (Zelda and Metroid games) I really expected better.
VALUE
Too short, that is the trend with many Nintendo games now a days. Since the GC game out, I've felt that many Nintendo games main game were too short if you just go for start to finish, and it once again proves true in NSMB. If you go to beat every single level and get every special coin, you may get around 20 hours out of the game if you are an experienced gamer. Thats good value for a hand held game, but for a hard core gamer like me, it took me 5 days for 100% completion, I was disappointed.
TILT
I wanted to rate the tilt lower, but it hurt the score too much to my liking. Tilt for me usually comprises of how the story got me into the game and my drive to beat it. In this game, there was a drive to beat it, to get all the coins, but the story was so terrible, I wanted to quit at the beginning. If you thought Sunshine had a stupid story, this game will make you think Sunshine had a master piece for a story. Basically, don't pay attention to the story, just go play the great gameplay.
OVERALL
It has great gameplay and graphics. If your looking for a fun week or two of gaming, this is the game for you. For people looking for a deep story and a lasting appeal to complete more than once, wait for Phantom Hourglass (Everyone saying its going to be the killer ap so its a safe bet to wait for it).
I enjoyed NSMB, just don't expect a rough ride or an emotional story. Expect a cake walk and silly story, albeit fun.