Too much. Spent about 12 hours on it since yesterday and I haven't left Flotsum.
The strange thing is, for the past say six months I've really struggled to sit down and properly play a game. I'd get agitated, or bored, or just want to move onto something quick and simple like Fifa. For example, Mass Effect 3 was hell, managed to grind through it last week and just outright didn't enjoy it.
This game's changed like the complete opposite. I leave party chat, crank up my headphones, close the curtains and just play it, and I can't stop. There's always another little quest to do, and even the little quests are so fun because of the combat and the items and the choices.
See, I'm typing like a lunatic. I've almost been romanticised by the game.
Thats how I felt about the game when I played it for the first time.
What impressed me the most was the characterisation in the game. I wouldn't have enjoyed it half as much if I was playing as someone other than Geralt. Guys like Dandelion and Roche are strong characters in their own right. Of course, its a well made game in its own right. Combat is very well done.
Enjoy it as much as you can.