At first I was a little skeptical about SECR's odd size, but that's due mostly to being used to standard RPG book formats for the better part of two decades.
I have to say that I really like the shape of the book now. It can be comfortably held in one hand, pages stay open far more easily without having to brace them with something, which was an issue with other RPG books when running a game and needing to reference a certain page or section during game play.
I also think the shape of SECR was planned so that the book could be stacked on shelves with other non-RPG Star Wars stuff. I've heard that several bookstores have done just that, so it increases the odds that a non-gamer will see the book and possibly check it out.
As has been referenced on the WotC boards, if they can get even a minute percentage of the SW fanbase that aren't non-tabletop gamers (which is a pretty large portion of the SW fanbase) to pick up and support Saga Edition, then it could potentially rival D&D for sales revenue.