Hi Bjeorr!
Aw, thank you! I'm really glad you enjoyed the original LMA. Sooo it'll be different for everyone, but I'd consider myself an Average-Slow reader...when I would playthrough LMA2 to get the entire sense of the game as a whole...I'd estimate it took me 7-8 hours?
Either way, I can assure you...if you loved the original, I feel like LMA2 delivers even more than the first. It's a slow burn horror by comparison/nature...but stay with it and I promise you, you won't be disappointed.=)