The interface is actually a bit confusing to work with. Stick with it and you get kind of used to it, but its still a little strange and some I wish some additional features were part of Trello, like syncing some emails with boards - to keep them in the same place as everything else.
Also, it lets you sync with some apps/services, like DropBox, but it doesnt let you sync with iCloud! I largely work in Apple Works on my iPad and want to sync all my project documents from iCloud! Instead, I have to export them to DropBox in order to connect them to Trello, then re-export the files to DropBox, replacing the existing file, every time I make an edit in a project document.
cwiren about Trello: organize anything!, v3.4.6