A solid platformer, but too short.
New Super Mario Bros. is a mix of SMB 1, 3, and Super Mario World with some new stuff thrown in. Each world (there are 8) has about 10 levels in each one. Most worlds have different exits that lead to different worlds, warps, or bonuses. Each world also has 3 star coins, which you use to get access to Toad Houses that you can visit once to get 1-ups or items. The new items here are the mini mushroom (which makes Mario tiny), the mega mushroom (which makes Mario huge for a short time), and the blue Koopa shell which gives Mario the ability to smash through blocks, provided he has enough room to run.
This is a fun game....for a few days. The star coins in each world aren't really too difficult to find. But once you find them, you use them to access a Toad House, but just once, which doesn't really make the hunt worth it, and yes, the hunt is pretty easy. After you beat the game, there's another use for the star coins, but that's not really worth it either. Sometimes you need to be mini or blue Koopa to access a star coin or an alternate exit, but since you can only visit each Toad House once, you end up running all over trying to find the right power up, which is really annoying.
You rarely get a mini mushroom, mega mushroom, or blue Koopa shell anyway, and they're rarely used or needed, which also makes them pretty useless.
This is a fun game for a few days...but after all the wait, and paying full price, this game is just not worth the money. It's a fun diversion, but there's just not enough game there. Buy it used, or wait a few months and hopefully the price will go down.