Too much white space and borrowed design elements that aren't consistent. I would make all elements consistent keeping the cool letter press effect.
Homepage: What you should do is position the screen shots to the right and to the left of it say "Improve your collab.." Under that add a little more detail about the software. I would need a little bit more information before I would want to take the tour or sign up. Currently I have to scroll down and get that information.
Homepage: I would get rid of the 4 icons and the entire box below it. And replace it with the tour page set up and content.
Registration: I would make the signup button shorter (in my opinion) and centered instead of spanning across the form box.
Overall, the letterpress effects and texture are good, but the layout needs to be rethinked.