My main takeaway from The Witcher 3 was "must find Ciri, the world is in danger!" followed by quite a lot of Gwent.

The Bloody Baron questline was probably the highlight, along with the Hearts of Stone storyline. The rest of it was going to question marks on the map, hoping to find something more interesting than a box to open or a surprise enemy attack. This got especially bad once you reached Skellige and had to faff about with a boat to reach half of them.