I guess I'm kind of concerned about the changes as well. Don't get me wrong, nothing against updating rules and CoC is far from perfect. At the same time, for me at least, the Call of Cthulhu rules have a sort of charm to them, even though there are obvious flaws to the system. Just hope it feels like the same game. At the very least I hope the changes aren't so sweeping as to make all of the previous CoC material obsolete. All I ask for is backward compatibility to some extent. It also raises the question how well it could integrate into the BRP rules. It's my favorite universal system so far.
On a minor note, I kind of hope for the monster illustrations in the bestiary section they go back to just showing the silhouettes of the monsters they had in previous editions, if anyone remembers those, rather than the way the have them fully illustrated in 6th. Leaves a lot more to the imagination (Of course, I really like how they did creature art for Malleus Monstorum as well.)
Just thoughts.