Link is a kid that lives in the Kokiri forest with other children and no parents, but he is the only one without a fairy, until one day. The Deku tree sends a fairy called Navi to visit Link after a nightmare where he sees a man with a black armor riding a horse. Once he wakes up he finds Navi who explains him that the Deku tree (protector of the forest) needs help. Basically you know that a wicked man called Ganondorf has cursed Deku on his way to conquer Hyrule and Link must stop him.
Your worst enemy... I mean your fairy Navi
The story jumps then seven years to the future with an adult Link and one of the ancient Sages who explains the situation. Those sages are able to seal Ganondorf but five of them are unaware of their power and Link, once again, has to search them and “wake them up”. In those seven years the world has turned into a chaos thanks to the evil king Ganondorf, but Link will have to explore each corner of Hyrule finding all of them. At the end, once all the sages are strong again, you will fight against Ganondorf who will be sealed and peace will be back to Hyrule.
The story, as you may understand, hasn't changed at all and it present us many of the famous elements from the saga like the Zora, the Goron, Temple of time, the desert... Also, until last year we knew this was the first Zelda in the chronology. Now we know that OoT is sequel of Skyward Sword and there's a funny detail about it; the instrument Zelda uses to show Link the songs for the Ocarina of Time is a harp, which is the main instrument (and it has the same shape) in Skyward Sword.
The gameplay is the same except for adding touch options that helps a lot in many dungeons. But the style of OoT was the base for later (and current) style. Probably I don't need to explain how a Zelda works, but well. The objective of the current quest (a sage, a Sacred Stone) is at the end of a dungeon that you will explore killing enemies, getting new items and keys to open doors to advance through the dungeon. At the end you'll fight against a boss to get a new heart piece. In Ocarina of Time our companion is the fairy called Navi that will be there “helping” (or being annoying most of the time) Link constantly. Although Navi is almost useless helping, there's nothing impossible in this game (the water temple is only annoying) but sometimes you are a bit lost and when you actually need help Navi doesn't give a f*ck.
Apart from the dungeons in OoT we will use the Ocarina in several places across Hyrule to teleport and accessing secret places. That's great cause even when you can save wherever you want you will start from inside a dungeon or in the Temple of Time as adult (or in Kokiri forest as kid) and that's not very comfy now cause if you are somewhere far away from the temple and then you save, you will have to make the same way once again.
There aren't a lot of sidequests during the game, apart from improving some items and collecting all the golden skultullas to help a coursed family you can trade with masks but that's a bit dull. Sadly this is one of the worst things if you play old games since you are used to new things that are way much deeper and long. But there's actually something new they've added, Sheik Stones. Like in the last Zelda, they are stones that show you a clue or a short video about what to do next and that helps much more than Navi as we mentioned before.
This is what we see now
For the remake as well as the touch options they've improved graphics. And now we have pretty good graphics. Keeping the main atmosphere of the original game, characters are much better and you can see more details everywhere. Even more, first time I played this game I checked how powerful is the 3DS moving the game without problems. This is nothing new. we saw the same with Metal Gear Solid and the remake for GC, but this time we have the 3D effect.
During the game I've been switching on and off the 3D effect and is something you notice. Not only when you get a new item and Links hold it for you to see how cool is on 3D, you can notice is everywhere; walls, on the hill, holding and running with a chicken (feathers look like are going to hit you)... it's something curious and fun. It's a great new way to enjoy games. Also when you are on first person view you can actually move the console like if it were your own view, so moving the console up you will see what's up there, that's cool.
Music is the same as the original composed by Koji Kondo of course, maybe some arrangements but why to change the original soundtrack if it's perfect? The ocarina songs are classical melodies in game history among other songs as the Kakariko village or inside house ones. Also there aren't voices (as always) expect for the typical Zelda sounds; screams, moans, whispers, yells and laugh from most of the main characters.
The only new song in the game
The final conclusion is simple, it's Ocarina of Time, what else do you want? I mean, just for the nostalgia factor you should play it and you will enjoy it a lot since is still challenging and epic. The 3D effect and new graphics makes it much better and attractive. Although maybe we've been used to many new things to enjoy it the same as in 1998.