Between the main quests, the hoarding, the side quests, the hoarding, the "visiting everywhere I can", the hoarding, the brothel and finally yet more hoarding, 150 hours? A good month and a half maybe, hard to say, I expect a lot of contemplation so it will take a long time for sure, talking about the first playthrough only of course.
One to thee months of acutally playing the game regularly. In the middle of that one to three month period, i'll be at university QQ
Well, it'll be interesting if people come back later and say how long they REALLY took.
I have absolutely no idea. Probably depends on how many times I die and have to reload.
I've stopped calling myself a completionist a while ago. There was once this weird gamer pride in that title, but now it just seems dumb to me. When I was running over rooftops in Venice to find feathers, I had to ask myself "wait, am I actually having fun right now?". Then I said to hell with that" continued with the main quests, slept quietly and never touched the game since.
Obviously (obviously, right?) TW3 won't have these soulless tasks, and since it's an RPG I'll have that urge to speak with every man and open every door. But there comes a point, especially when the game is this ridiculously long, that it'll really need to earn it, to make things more interesting than usual for me to continue the thorough exploration. So far the environments look great and I think I'll just walk around for their sake alone, even if there isn't a chest behind every third tree.
Oh, and is there a way to see how long you've played if you're not on Steam, and the game doesn't do it for you? Some data hidden in the save files?
Obviously (obviously, right?) TW3 won't have these soulless tasks, and since it's an RPG I'll have that urge to speak with every man and open every door. But there comes a point, especially when the game is this ridiculously long, that it'll really need to earn it, to make things more interesting than usual for me to continue the thorough exploration. So far the environments look great and I think I'll just walk around for their sake alone, even if there isn't a chest behind every third tree.
Oh, and is there a way to see how long you've played if you're not on Steam, and the game doesn't do it for you? Some data hidden in the save files?
I expect to beat the story mode in about 30-40 hours. If sidequests are interesting I will play about 100 hours.
Over and above I am a completionist too, I am a contemplative photographer, from those ones who take different views on different angles of the same items, and return later for have more views under different lights... so... the answer of the poll could be very very misunderstood by many of you. 
http://raptr.com/
I'm using this tracking app all the time while gaming. You can also track your games manually with it if you don't play on the usual platforms.
It will take pretty long for me. I will try to finish every single thing in game, I will play on hard/dark and I intent to not use witcher senses at all and only time saver I plan to do is fast travel. So yeah...lot of time will die in my TW3 playthrough.
As I have a young, 5 month old daughter now, and personal free time has become quite a luxury, I guess I'll need the rest of the year to finish the game. I'm surly not going to rush it ^^
Not for 100% sure, but i assume if you go normal pace you ll need the time devs say now.
High chance to need even more time than that, because we will enjoy the game on
a whole other level than the developers.
On the other hand... there are for sure some SPEEDRUN fanatics they have the wish
to "BEAT" the game as fast as possible ... maybe only t "prove" CDPR estimated the
time wrong.
But you can be sure such a speedrun has NOTHING to do with "playing" the game not
to speak of enjoying the whole thing.
High chance to need even more time than that, because we will enjoy the game on
a whole other level than the developers.
On the other hand... there are for sure some SPEEDRUN fanatics they have the wish
to "BEAT" the game as fast as possible ... maybe only t "prove" CDPR estimated the
time wrong.
But you can be sure such a speedrun has NOTHING to do with "playing" the game not
to speak of enjoying the whole thing.
I have lots of distractions especially job and studies. So it will take lots of time for me to complete it. I guess I might finish it within 3-4 months after starting the game. And Witcher 3 might be my only game this year. The second playthrough might be faster but who knows. I actually would like to play through the game at least 2 times in this year.
@TheEvilChris Forgive me for asking in this thread but since you mention the above in your post can I just ask you if every build in Novigrad, Oxenfurt and smaller villages enter-able or are the majority of buildings "closed off/looked"?
It would be nice to have a abswer to this question from someone that has hands on experience with the game.
I need to rush nowhere.. i think it took 150h of my game time. I want to explore as much as possible and finish so many quests as i can.. Besides, i go for Hard mode on my first run