Ok, I've just finished this and I don't think I agree with the point about the three main characters (the Bones') arcs being weak.
You get the feeling that Fone Bone is indeed the brotherly bone, trying to keep everyone together and level-headed, while Phoney Bone is out trying to get rich quick and back home to Boneville just as quickly. And then Smiley Bone is just a happy-go-lucky guy, but we also see that at times he can be very serious and does have a heart. Also, Phoney is seen at times as a caring Bone who's just trying to look out for his cousins.
And that's what this is mostly boiled down into. A small family of orphans who've gotten lost and into some kind of great big epic fantasy tale that they don't really need to be a part of.
Yes, there are certain constraints that the artist and writer are bogged with in the comic, but there are also boundless possibilities that they can achieve as well.
Oh yes, EUOL, did you, a writer, spell "albeit" incorrectly? =P