I have played and beat this game and I have to say it is one of the best Mario games I've ever played although the game is extremely easy(except for the last world) and can be completed through dedicated playing in about a week and when you beat the game you can go back through and play any of the levels or look for levels you missed and even play as Luigi by in-putting a code seen by finished the game. Overall, an excellent DS title that brings great graphics and excellent controls(they managed to incorperate some of mario's 3d platforming moves like wall-jumping) I also thought this was a great throw back to the old mario and it felt like that all over again. I haven't had this much fun with a mario game in a LOOOOOONG time.
While I found the game to be very faithful to its roots, that was just my problem. Having started my gaming career on Super Mario Brothers, I felt like this was just ANOTHER rehash. No real changes, just new maps. If you are a huge fan of SMB 3 or SMW. Then by all means, give this a whirl. If you say, yeah those games were cool, but I want something new... you will be disappointed here.
New Super Mario Bros. is definitely a welcome blast from the past! However, its not just the nostalgia of this game that makes it great. There are several variations and additions to the old 2-d platforming model that adds greater depth. Its a must-have game that belongs in any DS collection.