The atmosphere, exploration, challenges (whether puzzles, enemies, dungeons or whatever), development (items, heart pieces), secrets, and of course, the combat.
Some Zelda games focus on these elements more than others. Wind Waker, for example, is one of the best looking games ever - the characters look amazing, the water, the islands, everything. I love the way the story plays out - it's just really simple and has its own charm. Unfortunately, it suffers in other areas like combat (one of the easiest games ever) and adds unnecessary downtime (sailing, brb taking a piss).
I'd have to agree with Rol that the enemies need to pose a threat. Having each upgrade significantly improve your progress is something that can really feel satisfying (see: Monster Hunter). I'd love it if all the different weapons were actually useful in combat, so you'd switch between them depending on the situation (sort of like, say, Mega Man), rather than use them primarily as tools for solving puzzles, or hiding secrets.
Actually, I think Zelda can really benefit from taking a page out of a game like MH. There's nothing like the feeling of, "How the fuck am I gonna kill this thing?" and the sense of accomplishment you get when you bring it down. In Zelda games, for nearly every boss you just end up using the dungeon item, and the goal is to figure out how to use it against them (something like a puzzle)... I think it'd be better to mix things up a bit, and give the player multiple ways to down bosses / enemies.
They could definitely use more bosses or enemies that make you think, "How am I going to hurt this thing without getting hit?" rather than, "How do I hurt this thing?"








WHO IS JESUS REALLY?