Being only the second game in the Zelda series, it can't be said that there was an established format for the series. This is, as stated above, a great game; combining a gigantic over world map with wandering monsters, which then converts to a side scroller to fight the various types of beasts. Link can go to towns and converse with the local populations, explore caves, temples and the like. Unlike in the first game, Link can now gain experience, learn new sword techniques and cast spells!
The story begins after the original "Legend of Zelda" with Ganon's minions trying to resurrect their fallen master by sprinkling Link's blood on Ganon's ashes. The storyline is very deep brought to life by the expanse of the world map and the depth of the game play and exploration. Highly recommended game for any fan of the Zelda series.
I know I'm leaving stuff out, but I hope this description will help anyone unfamiliar with the Zelda series.