A challenging old school Ninja classic.
Right off the bat you'll notice that this game is definitely tough, there's no doubt about it. The NES era in general seemed to produce games that were more tough than games being made now days and Ninja Gaiden still stands out on the harder end of things. But it's really a great game.
The game features an excellent array of enemies ranging from simple bats to street thugs, most anyone you wouldn't want to encounter on the streets is here to stop you dead in your tracks and they are pretty good at it to. The sound in the game is outstanding, I love hearing the music in this game because it's so upbeat and original. Honestly, as a sound track it would be awesome.
The gameplay feels really advanced for it's time. It's your typical side scroller, but it features a lot of non-linear levels. It had a lot of platforming, but not like Mario where you just jump platform to platform, it required you to do a lot of wall jumping (Ryu could stick to walls and then jump off) up and down and really use your environment to get around. And of course there were enemies at every turn ready to stop you in a heart beat.
On top of your normal sword attack you could pick up numerous power ups that allowed you to throw shuriken, windmill shuriken, circle slash when you jump, or do some ninpo like cover yourself in flames deeming you temporarily invincible. The game still has some of it's glitches such as when you get hit by enemies sometimes they'll get stuck on you making it ten times harder to get away without dying. All in all though I found it's flaws to be forgiveable and the experience to be enjoyable (as long as you don't take it to serious and get upset at it's difficulty). The Wii also helps you out a bit with the frustration with it's VC savestate type feature so you don't have to complete the game in one sitting (it's not recommended to try to do so). This is a childhood classic for me and it's great reliving it and being able to have it anywhere I take my Wii. Definitely near the top of my VC recommendations.