The game is great and all, but 50 hours in, it gets so frustrating that i can't finish most quests because of bugs!
To make a list:
Tarquin's Quest with the blade, he doesn't leave the ship when you bring him both blade parts, so he is nowhere to be found on his whereabouts marker on map.
Treated like Cattle quest, you can't finish it, you give the potion to the second cow, she says it's working but nothing happens.
Fane's Blackpit mine quest. I went through the whole mine and killed the Eternal Aeterna, gathered all the tablets, but his quest didn't progress.
Apart from these, i really can't tell when a quest is over and when it is not, because most of the time it says it's closed, but sometimes even though you did everything in the quest, it's still there, making me wonder what i should do next. I think there must be a huge patch solving all the quest bugs.