Are there still a lot of bugs? Are the bugs just mechanical or is content bugged? Will I miss out on content with the game's current version is what I am asking I guess?

Part mechanical and part content, including some quests. You'll probably won't miss many important things though.

If the question is play now or never, I'd say play now. If it's play now or play in a month, waiting a month for them to iron out the bugs would probably more enjoyable.

Most people complain about the difficulty in encounters, but this can be adjusted even just before a fight if it is too hard.
Many also complain the kingdom falls, while you are out questing (I leave mine on Auto and had no issues so far).

I think the world is not set up to have a baby-zone around the start and then become progressively harder. If you die, don't go there yet is my opinion. Remember those finger of death in Baldurs Gate like areas.

Some people have serious issues, like crashing clients.
Some have content issues with quests not working.

I had one crash in 1.0.6 I believe (Nullpointer reference for a texture which has since been fixed in the area), since 1.0.0 and I played yesterday on 1.0.8b, playing all versions in between.
It did not keep my graphic settings until 1.0.7 and some translations into German are still missing in 1.0.8b. Like the talent Adori-Dualist says "(Adequate)" for the weapon requirements description in the German translation.

What I miss is some guidance after you got your kingdom. You will then just run around and discover or do tasks for the kingdom to grow. With the curse hanging over your head, there seems to be something cooking up.
There is little questlog about things, like the whole Tristian dialogue about the curse is nowhere written down, but I remember he mentioned the curse once and also the temple of the Elk.
Yesterday an update triggered and there seem to be intelligent trolls being a new threat in the kingdom...

it still has a lot of bugs. Me for example are stucking at the point, that the game crashes in the tavern. whenever i go there, the game crashes.

"Error: object reference not set to an instance of an object at Kingmaker.entitysystem.persistence.sceneloader+<unloadareacoroutine>c_lierator7.movenext () [0x000a7] in <c4345743787d45aca08a9eb3c61109fd>:0

And as my companion quest is there, which i would like to solve, i just wait.

Aside of this, in steam the people complain about broken side quests and some other stuff.

I see lots of people have this, must be at a certain point in the companion quest only.
Well, I sent Valerie to go where pepper grows :)

Its not Valerie, its Amri. I am in chapter 5, somewhere around the tournament. She wants to speak with me about, how to deal with the ghost.

At the same time, the gnome wants to solve his quest, too. and it involves the tavern, too. But in his case, i did not start the quest, as it was bugged the first times i tried. and now the tavern breaks all the time, even as i did not start his...

Yeah, I wish I had more time, not sure which chapter I am.
Where do you see this?

I got the kingdom and some curse triggered.

You can´t really see it. You have to check the walkthrough pages. They give you some hints, where you are at this point:

https://www.gamerguides.com/pathfinder-kingmaker/walkthrough/chapter-4-the-twice-born-warlord/armag-s-tomb-part-1
(left bottom: content menu)

Its not finished, as the game is terrible bugged at the later chapters. At steam some guys were able to finish it, but only with a lot of cheating, like going through walls.
All together you should have 7 chapters, as i read in the forums.

Very.

Patch 1.08b broke something VERY important.
https://www.gog.com/forum/pathfinder_kingmaker/flintrock_grassland_problems_in_hotfix_108b/post1

Chapter 5.
First quest was broken. Dialog with green whore[fairy] in the temple endless.
And rhe second question.
Why armor on the baron after cut-scenes dissepeared? and all game I can see only class shirt.

???

Oy, sorry only emotions. Fairy at russian Хранительница цветов.

Just ran into a gamebreaking bug in 1.08 that causes a recurring drunk giant event to repeat endlessly and eventually destroy my kingdom (nok nok quest triggers it).
Performance has also taken a huge hit overall. I can run Ethan Carter in vr on max at 40+fps, but this 2d game keeps stuttering and dropping below 30fps..

Thats not a bug as i know of. Its just hard to solve. I did it as fast as possible, and it gave me only some smaller minus.