Always interested in this, it's notoriously difficult to gauge with adventure games!

I only had direct feedback on this from one person so far, he said 8-10 hours.  Yes I know, the other problem with this is that most people don't actually take much notice about how long they are playing! :-D

It took me roughly 8 hours to play (including 45min of the Demo, didn't even finish and decided to buy mid play)  :-)

Thanks so much Das Wasser!  Hope you enjoyed those 8 hours :-D