Started and finished this game fairly quickly. I haven't seen the movie yet, so now I'm curious if the movie follows the game. If so, it doesn't really follow the book but the book is short in comparison to a movie and they added a bunch of stuff in the middle.
This game has collectibles but everyone said don't worry as you'll get a cheat later on. Well in order to get the cheat you want in order to find all the items on a board, you have to find everything on a certain item to unlock that cheat. So as you're running through, you still need to try to find everything you can and towards the end of the game, you'll start unlocking all the cheats. At least when you're running back through, you can run until you find it and not worry about looking everywhere again.
The gameplay is very simple and not hard at all. Fighting and saving the monsters gets a little harder later on but all you need to remember is, not die of course, but keep knocking the black stuff off the monsters so they will stay up and not get pulled down into the ground.
So in about 10-12 hours you should be able to knock this game out fairly easy.