The original Legend of Zelda can't help that it was continuously outclassed by its offspring.
This element forms the basis for the first Zelda-game, which lets you play as Link for the first time, as you guide him through forests, caves, shores, and dungeons. For its time, The Legend of Zelda was an extraordinarily non-linear game. It did require you to perform a set number of actions, but how you did it was entirely up to you. Although the RPG genre already existed at this time, this kind of freedom within a video game was very unusual back then.
You view the action from a top-down perspective, making it easy to anticipate and dodge the attacks of whatever enemy you may run into. Of course, rupees can be collected to purchase new items, such as weapons and keys. The fighting element is still as basic as you'd expect from a NES game, though it must be said that the focus is on puzzling and navigating much rather than action, for the most part. The (considerable amount of) time you spend in the overworld will be accompanied by the famous Zelda overworld melody, which is a plus for every Ninty fan.
Although the game can be good to relive old times, or to discover where your fancy 3D Zeldas came from, it is by no means a necessary addition to your Virtual Console. It obviously has a lot of nostalgia going for it, but the game hasn't aged as well as, say, Super Mario Bros. 3. The concepts innovated in The Legend of Zelda, which were remarkable for their time, mind, have been implemented in nearly all subsequent Zelda games in a much bigger, better, and smarter way. The experience just isn't very compelling after you've played A Link to the Past, or any of the 3D Zeldas for that matter.
So if you feel like spending 500 Wii points on a game because of its historical value, keep in mind that the odds that you will end up not playing this game for more than an hour are rather high. The Legend of Zelda isn't a bad game, certainly not when you view it in its proper context, but it can't help that it was continuously outclassed by its offspring.