One thing to note is that this film was really violent, which was something that the green-band trailer hid well. I'm reminded of the same thing happening for Pan's Labyrinth because I though that it was a fantasy film, not a violent war film with fantasy elements. So like that, I didn't enjoy it as much and was unfortunately surprised by the brutally. That aside, I wanted to like the story too but I didn't feel that there was a huge payoff and left the theater with so many questions. I ended up searching online for a summery when I got home, but that's no way to experience a work. It should stand alone without a written exclamation about what's happening.
Also the story would have been stronger if the events were presented to the viewer in sequential order like in the book (not that I've read it), and not mixed up like it was in the film. That would have given the audience little morsels to ponder about one at a time, and help give reason to appreciate the direct connections that impacted the future for certain characters and events. Which perhaps would have given the viewer a more substantial profound experience.
Overall Cloud Alas is something that I won't recommend, but if one is still curious about it, wait for it to come out on Blu-ray/Streaming. Again, ambitious is the best way to describe it.
Cheers and happy movie watching.