The ipad does not have a digitizer built into the screen so getting good stylus input is a bit of a trick that requires an active stylus and good app support. The Jot Script is trying to simplify that experience but being brand new is not quite ready for prime time.
I think the currently most accurate combination you can get is Goodnotes with the Jot Touch.
For drawing you might try the new Pencil and the accompanying Paper app.