Zelda II: The Adventure of Link is often referred to as the black sheep of the Zelda family. Unlike the original Zelda games, the top-down perspective is replaced in favour of side-scrolling platform action, similar to that found in Castlevania.
Perhaps more significantly than that, it is the only Zelda game to offer an RPG levelling-up system. It also has a large overworld map with caves, towns and palaces, not to mention random encounters with baddies. Throw in a number of subquests to complete which allow you to obtain vital skills and items which became a feature of future Zelda games, and there's a lot going on.
So is this game as bad as some would make out? Well no, not really. If you take it for what it is, the game is actually very entertaining. It does have its share of flaws and lacks the timeless quality of the other Zelda games, but compared to many other NES titles, it stands up quite well over time.
Let’s get this out of the way now, Zelda II is a tough experience. Not in a challenging way which is fun, but rather it can be very frustrating. When you die and choose to continue you’ll have to start the game right from the very start; this is a game crippling flaw meaning you'll have to traverse the massive overworld and take on all those random baddies again, just to make your way back to the palace for another stab at completing the game. One repetitive trip across Hyrule too many and you’ll want to throw your controller at the TV.
The dungeons are simpler than a regular Zelda game too, and don’t really require any logic to complete. There are no puzzles to speak of, just the hack, slash and kill mechanics of a regular action platform game, which would be fine if this wasn't part of the Zelda series. The overworld is a particular frustration for the simple reason that certain vital items are hidden in unmarked areas; did the developers seriously expect that gamers would want to trace every square pixel of the game in the hope of finding something, with no clues?
Despite the flaws mentioned above, there are a lot of good things to be said about Zelda II. It is at heart a good old-fashioned Nintendo adventure and still has the charm to entertain after all these years. For Zelda fans this is a slice of history you should delve into, however for newcomers to the series it's recommended that you start somewhere else, namely the excellent A Link To The Past on the SNES.