According to CD Projekt RED, The Witcher 3: Wild Hunt could last you over 200 hours. Senior Game designer Damien Monnier answered a tweet about the games length, noting that you could spend around 200 hours if you want to do complete everything.
@Ryldux mmmm hard to say, if you do everything I d say 200+ hours.
— Damien Monnier (@Bacon_is_life) March 29, 2015
The game will be at least a 50GB download on the PS4, so this is not a big surprise.
The Witcher 3: Wild Hunt is scheduled to launch May 15 for PlayStation 4, Xbox One and PC.