A high 7, but even as a lifelong Zelda fan i cannot give it an 8 whilst I'm running away from every fight.
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Start with the good.
Environment, Exploration, & Adventure.
The open world is the most breathtaking I've ever seen, as soon as you get out of the starting area and in to the light you can see the endless hours and talent that were put in to building this artistic sandpit. I was afraid when I saw the world that they spent so much time building a landscape that it would be sparse and repetitive, but behind every corner is a new discovery, climate, adventure, or surprise.
I go off on a short task, before I know it I've spent hours on a long unexpected exciting adventure.
The environment feels fully interactive (short of burning down villages and going on a rampage... this is Zelda, play nice...). The objects are extensive and all have a purpose and will react to your actions, its the little things i find most impressive i.e. i mistakenly set a blue chuchu jelly on fire and it turned into a red chuchu jelly. I put sticks on the ground and set it on fire, suddenly i have a campfire. Every time you do something and think the game won't know what I'm doing it almost always does, it is like magic.
The world is superbly ambitious, detailed, varied, beautiful and populated. I cannot praise it enough, the best I've ever seen, it is well worth buying the game for the purpose of exploring Hyrule alone.
On to the bad.
Story
its Zelda... unless this is your first time you know the story and you know its not changed in 20+ years it aint going to change now. I will forgive an average cliche storyline and move on.
Combat
I get no sense of joy from combat in this game, it is frustrating and unrewarding and i find myself avoiding it wherever possible.
Like many people I have played every major Zelda game from the Super Nintendo (6 years old?) to now. I like to think that I'm an experienced gamer and I'm at the age now where i like a challenge from games, and yet i find myself avoiding fights wherever I can. I should want to charge in sword and shield in hand to take on goblins and skeletons but i just cant bring myself to do it.
The fights feel slow, your character is sluggish, your attacks do little to no damage, and you can only survive a handful of hits at medium level (2-3 if you are lucky), your attack options feel limited for a modern game, hit (in one direction only), dodge, block (if you have a shield). You can use your bow but the aim button feels extremely unstable, trying to line up a shot is way to difficult and when you hit (even if its on the head) it will often do next to no damage. You can use bombs as well of course but they wont really do anything.
The world is populated with extensive varied weapons, shields & bows, you can take the weapons from enemies you kill (a common mechanic which i love), you find them lying around, or you collect them from chests. However, weapons will break and be irreparable after a handful of hits.... it is so frustrating. It is hard to convey how bad this is until you experience it. Dependent on what your weapon is and what you're attacking i'd say it feels like 20 hits per weapon (or uses of bows or hits on your shields), when you do no damage and enemies often take many hits to kill... weapons you painstakingly gather barely last a fight. Add to this that you can only carry a handful at a time and you can't store them anywhere the hunt for weapons shields and bows is constant... someone at Nintendo obviously thought that was a good idea... they were wrong... very very very wrong.
You have to tailor your weapon and armour to what you are fighting based on element, which is good and fine... everyone else does it... but this is Zelda! I want my green tunic, sword, shield and bow and i want to go carve down hordes of monsters! Then i want to feel that sense of reward for winning and an actual reward for my character.... at the moment i have five sets of armour which i have to change for each fight 6 flimsy swords and bows which do no damage, and will break after a few hits, and the knowledge i have to hit my enemy 10-15 times (with little variation in how to hit them) but they just have to hit me 2 to 3 times (with my sluggish dodging and blocking).
I don't find joy in fighting, i don't find reward in winning, and for winning my prize is often a weapon which is worse then the 2-3 i just broke in the fight...
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After the outstanding world which Nintendo has created i feel sad giving this a 7, if they fix combat balance & weapons breaking then its a 9 or perhaps a 10... but i cannot give it higher then a 7 whilst i actively try to avoid combat.