If you want a different kind of Zelda experience, this game is good enough.
In this game, Link is supposed to find the Triforce of Courage to awaken a sleeping Zelda (It's a different one from the first NES Zelda). The followers of Ganon are trying to kill him to revive Ganon. Since this is an NES game, the story is really simple, but I was just saying this to tell you what the game is about.
Alright, onto the actual review. This game isn't like all the Zelda's we know and love. The view of the game when you are in the overworld is similar to most 2D Zelda's, except you can only use two items: the flute, and the hammer. The main gameplay takes place in little action segments, where the game presents itself like a 2D side-scrolling platformer. This is also where the game gets more interesting. The combat is more strategic than most Zelda's, as you have to hit an enemy from either a high or low position. There is also an RPG leveling-up system. Killing enemies yields experience points that let Link level-up his health (so he doesn't take so much damage from enemies), magic (where you can use less magic points), and strength up to eight levels. There are places that present itself like a platformer, where you need to navigate perilous places kind of like Mario would. These changes all make for a fun experience that's vastly different than most Zelda's, but there are somethings that hold the game back. Specifically, it's hard. I died a lot more times in the original Zelda, mind you, but that doesn't change the fact that this game gets really hard in many different ways. One way it's hard is that many enemies can steal experience points (they can't steal anything leveled-up, thank goodness); another is that many of the platforming segments have enemies fly at you and can knock you off platforms a lot of times, killing you instantly (if you're good at platforming, then these won't be too hard); also, this is the only Zelda to feature lives in it, but you only have three of them (save the fact that you can get a few more), and if you lose all of them, you start back at the temple at the beginning of the the game, with all your EXP gone! I could keep going on and on, but let's just leave it at that. Nintendo is at least fair in the last temple, as the second-to-last boss will be killed for good if you kill it once, and if you get a game-over, you start back at the beginning of the temple.
It gets bad at parts, but these things all make a fun game. This Zelda also introduced several Zelda standbys. Like, for instance, the magic bar and spells are first introduced here (why hasn't that been seen since The Wind Waker?). There are also towns, with better NPC interaction (let's all not forget the interaction with the guy named Error), and side-quests to partake. And, of course, Nintendo introduced the most important thing to the whole series: the full shape of the Triforce!
Let's also talk about the presentation to the game. The graphics to the game is fine for an NES game. The looks to each place is pretty well detailed, but it's not the best looks to the NES. The music is fine as well. But sadly, I think I saw the IGN.com review for this game say that the music wasn't even done by Koji Kondo. So while the music sounds good, it's mostly forgettable.
For a sequel, this game does a lot of new things, and these things are quite fun. But the difficulty of lots of parts can drag the game down, making this one of the weaker Zelda's. Oh well. I didn't think the original NES Zelda wasn't too great either. The Zelda didn't really came into their own with A Link to the Past on SNES IMO.