Based on reviews score it's 98 (honestly I haven't seen such high score since I remember) but players gave it only 78. 
I can't decide if I should buy Switch but seeing this score I guess I should but console for this game only.

So I am asking you. What are your opinions on Breath of the Wild (even if you did not finish game yet). Is this game worth buy console for?

i'm pretty sure the 7.8 score is mostly due to trolls. I haven't played it myself because no switch yet. but people here on this site say its very good.

I hate numbered reviews. I am not a big Zelda fan. Some of the games I dislike. I even skipped SS because I was tired of the formula since OOT (tho I still love Wind Waker). I can say playing it. It's a damn fine game. Easily the most well made 3D Zelda. Might even top LTTP. I do have some issues like not a fan of Ubisoft Towers but at least figuring out to get to the top of each one in itself is a puzzle. I can say it's a seriously fantastic game. Gone are pushing blocks. The dungeons in this are very unique not just to Zelda series. You really think on your feet a lot. The game doesn't hold your hand. I like that it's up to the player to get very creative in whatever you want to do. There is no real wrong way. Many games promise freedom but still make you play by that games rules. Botw is one of the few games where you are truly given absolute freedom in every aspect. It can be overwhelming at times but that's a good thing in this games case.

The 78% is just troll reviews. It is obvious when you read them.

The game is definitely in my top five best games of all time. That puts it above a 95 at least. It isn't that there are any single new gimmicks that the game revolves around, but rather a multitude of new things combined with a great attention to detail. The world makes you want to explore it, and gives you all of the freedom to explore it how you wish, but it does this without copying and pasteing things. Every shrine is obviously different and well planned. Every camp is different and changes dynamics. Each forest has different things to find. So on and so forth. The world design is planned out well so that you are not constrained in what you want to do. The main quest is nonlinear unlike other open world games where you have to do things in their prescribed order for it to make sense.

And then if we look at the close details, everything is well crafted. Horses aren't controlled 1:1, but rather rely on a multitude of intuitive dynamics. Cooking is intuitive. Even combat is intuitive. You think not in game logic, but real-world logic when you are playing. That is awesome, because it adds a lot to immersion.

The game sets a goal to be totally nonlinear, and for the most part it succeeds flawlessly. For example, I can go fight the final boss without completing anything else, but there are consequences for this. I can go explore and I will be rewarded, not just by gaining equipment and resources, but because it is fun to look at the next mountain and see what is there. And the game is so dense and diverse that you don't know what to expect.

So yes, I think an A+ score is warranted. Whether or not it is a 96, 98, or 100 it does not seem to matter.

I don't think any game is worth that much.

You may not believe this, but I have never played any Zelda game (my only Nintendo consoles were GameBoy Advanced and 3DS). So I have another question. If I consider Witcher 3 and Persona series as great games and I enjoyed them will I also like BotW?

It's extremely good and definitely deserves the 98. It's spectacular.
Read the negative reviews on Meta. They're salty trolls lol
^Tivec. If you like Witcher 3 you'll like BotW :D

Te witcher 3 is great especially if you play on the hardest mode and plan before every battle

I'm enjoying it but, even as a Zelda fan, it isn't the greatest thing, ever. Not yet, anyway.

That is okay, Breath of the Wild is very different from other TLoZ games. In fact you'd have to play almost every game in the series to get an idea of how Breath of the Wild might play, because it takes bits from different games, but also adds a lot of new things from other series, and has innovations of its own. 

If you like The Witcher 3 because it has a very beautiful, expansive, and unique world which you can explore every detail of then you'll like Breath of the Wild. Don't expect as scripted of a story and side-quests as The Witcher 3 and even Persona though. The story in Zelda games is mostly based on world-building rather than characters and drama. Although that has been changing a little recently. 

Since you are not invested in the series (yet), it would be hard to recommend the Switch if it is the only game you are interested in for the future. Xenoblade Chronicles 2 would be something else you'd like, if you find The Witcher 3 and Persona fun, because of the way the story works and the scope of the world. Otherwise, you should look at other upcoming Switch titles and maybe just wait for them to release. I usually have a five game rule for myself. If there are five games I can see myself buying, and I have time for another console, then I will get it.