One of the Greatest Games Ever.
Blaster Master is not only my favorite game for the NES, but I believe it is by far one of the best games ever. It's so much fun. I think that everyone in love with old school NES games needs to try this game. Although it may be a little on the hard side (mostly due to the fact that there is no save feature so you'll have to do it all in one sitting), a game genie can help you experience this great game all the way through. The mix up of two different playing styles can add a really diverse experience, especially for an NES game. The soundtrack is outstanding, probably trumped by only one other NES game, The Legend of Zelda.
If you haven't played this yet, do so now. I'm sure you won't be dissapointed.