I'm confused at why some peoples times are so high... mine was around 10 hours... I got every lore entry, every quest, etc, etc. There are no NPC's to interact with other than quest givers, no mini games, really nothing to do other than the main quest... The only way I can see people taking so long is people getting stuck on boss fights... I played on hardcore and learned the encounters fairly quickly... they only require a few tries to learn some of the harder ones and then another try to execute it all... I find it very hard to believe it took you another 7 hours on top of what it took me to learn such encounters... unless of course you are generally bad at video games?
First playthrough = 10 hours... any playthrough after 5-6 hours.
Yes, naturally anyone who says it took them longer to finish than it took you is not telling the truth.... Or must be really a bad player.