Adventure of Link is disliked so much by some gamers because they are used to the modern games and other types of Zelda games altogether. Adventure of Link was like no other Zelda game in the fact that it was side-scrolling. No Zelda game since then or before then was side-scroller except for some small parts in games like Link's Awakening, Oracle of Seasons, and Oracle of Ages. Adventure of Link is different, and it's also very hard. Both of these contribute to why most gamers tend to dislike the game. Most people who pick up the game don't even have the decency to finish it, and some people don't even have the ability and skill to finish it because of the difficulty. That may make some people appreciate it a little less, but it doesn't necessarily make it a bad game.
Adventure of Link had high points to it, and I believe one of the greatest ones was the magic spells. The spells were a great idea, and they worked awesomely in the game. There are other things to the game that made it a bit better, but it's been so long since I've played the game, and I have never replayed it once. I do know that the game wasn't horrible, though. People don't give it as much credit as I feel it deserves. It being a Zelda game already makes it 100% better than games from other series, so it's certainly not a bad game. Whether it was a bad Zelda game or not, though, is up to debate. I feel it was no worse than some of the Zelda games we've been getting recently.